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Series / NUMB3RS

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We all use math every day. To predict weather, to tell time, to handle money. Math is more than formulas and equations: it's logic, it's rationality, it's using your mind to solve the biggest mysteries we know.

A Police Procedural revolving around an Odd Couple of crime-solving brothers. Don Eppes (Rob Morrow) heads a team of FBI investigators called on to solve the exceptionally sensitive and baffling crimes that happen in Los Angeles about once a week. To solve these highly complex crimes, he invariably turns to his brother, Charlie (David Krumholtz), a college professor and mathematical prodigy, who applies pure mathematics to the task of solving crimes.

Ultimately, math conquers all...though on the way, Charlie usually faces a crisis of faith stemming from the fact that, while he's a mathematical genius, he is emotionally immature, with only a very slight understanding of human motivation. Balance is restored via the assistance of his father Alan (Judd Hirsch, a veteran of three other TV series produced by Paramount) and physicist colleague Larry (Peter MacNicol). Larry generally advises him to steer clear of messy human-interaction problems, while Alan nudges him toward a better understanding of human nature.


The show finished its sixth and final season in 2010.

The show's storylines were supposedly inspired by actual cases.

7his series provides examples of:

  • 555: The fifth season finale uses the IP address
  • Absentee Actor:
    • Alan (Hirsch) doesn't appear in the season two episode "Dark Matter".
    • Larry doesn't appear in much of season three due to MacNicol's commitment to 24.
      • Previously, he didn't appear in the season two episode "Backscatter".
      • He also doesn't appear in the episode "The Fifth Man".
    • Similarly, Megan also doesn't appear much in season three due to Diane Farr's pregnancy.
    • Colby (Dylan Bruno) doesn't appear in the season three episode "Provenance".
    • Only Don (Rob Morrow) and Charlie (David Krumholtz) appear in every episode.
      • Additionally, Krumholtz is the only actor to appear in all the aired episodes and the original unaired pilot.
    • Advertisement:
    • It's particularly egregious in the last two seasons, where there are technically four other agents in addition to Don (David, Colby, Liz, and Nikki) but only a few episodes actually feature all four of them; in most episodes, only three agents appear while the fourth is entirely absent. In most cases, the absences are not explained or even noted, although one episode ("12:01 AM") does say that Colby, the absent character of the week for that one, is on a fishing trip.
  • Absent-Minded Professor: Both Charlie and Dr Larry Fleinhardt are prone to this. Charlie gets better as the series progresses, but Larry is prone to being so deep in contemplation of either physics, math, or philosophy that he forgets what's going on around him.
    Larry: Let me ask one thing. When we met just now, was I coming out or going in to the library?
    Charlie: Coming out.
    Larry: [sighs] My memory is a memory. All right. [starts back inside]
    Charlie: [yells] Larry, you were coming out!
  • Accidental Murder:
    • The opening scene of "Rampage", involving a man busting into the FBI office and shooting everything up, ends with a fusillade of bullets, and one man dead: a suspected pedophile the team was interrogating at that moment. It turns out that Colby's bullet was responsible, on account of the bullet going straight through the attacker's shoulder, through the office window, and into the pedophile's head.
    • "Dreamland" involves a company trying to develop a less-lethal directed energy weapon, but the project proved to be more unworkable than anticipated. Eventually overconfidence and pressure from losing funding and being shut down caused them to take too many risks and even use themselves as test subjects, which turned ugly when the weapon proved too lethal.
  • Action Girl: Terry Lake, Megan Reeves, Liz Warner, and Nikki Betancourt.
  • Adult Fear:
    • Any episode that deals with kidnapping especially as the criminals responsible are shown to be violent and not above killing the people they take to prove a point or tie up loose ends.
    • In "Bettor or Worse": Not only are a mother and daughter kidnapped, but it turns out the husband/father was responsible.
  • A Fistful of Rehashes: One killer accidentally triggered one of these situations through domino-effect killings (he shoots at Gang A, who retaliates against Gang B, who retaliates back, people get caught in the crossfire...repeat until about 150 people are dead) after his young son was murdered by gangsters. By the team the crew catches up with him, he has been very clearly driven insane from the guilt and winds up killing himself with his handgun.
  • A.I. Is a Crapshoot: Briefly holds Amita hostage and turned out to be fake.
  • All for Nothing:
    • Season 3 episode "Democracy" involves one of Charlie's mathematician friends being killed, along with several of her associates, on account of the research they were doing, which could possibly be used to rig voting machines and elections. The prime suspect escapes prosecution due to one of his subordinates taking the fall, but Charlie takes his friend's research and publishes it in the paper, allowing the state legislature to know exactly what to look for in the machine's software and stymie any attempts to rig the elections.
    • Season 5 episode "Sneakerhead" involves the theft of $250,000-value sneakers. The victim ends up basically stealing them back, but when he goes to look for them in the end, it turned out that his son found them, thought they were a birthday present for him, and wore them out in the rain.
  • All Guys Want Cheerleaders: In the episodes "Dark Matter" and "The Running Man", Megan asks Colby what he was into during high school and college, and both times his answer is "Cheerleaders".
  • All Your Base Are Belong to Us:
    • Season 2 episode "Rampage" starts with a man charging into the FBI office and shooting bullets around, almost catching Charlie in the crossfire.
    • In "Chinese Box", a former contractor holds David hostage inside an elevator in the FBI building.
  • Altar the Speed: In the middle of Charlie and Amita's wedding preparations, an invitation for a visiting professorship in Cambridge comes up for the two of them. Not wanting to rework or postpone their plans or burden their friends with travel issues, they decide to get married the very next day.
  • Alternate Reality Game: Chain Factor, an addictive little Flash game which went rather deeper, including clues scattered throughout one episode, online sites, and the Los Angeles subways to unlock various power-ups.
  • Always Gets His Man: Don Eppes.
  • Amazingly Embarrassing Parents: Alan Eppes can be this at times.
    • When Amita's parents come to California to meet Charlie, they invite a family friend — a young man about Amita's age — to join them for dessert while out to dinner with Charlie. Amita initially completely misses what's going on due to knowing the friend is gay, but when Charlie points out that her parents don't know the friend is gay, she realizes what they were trying to do and is mortified.
  • Ambiguously Jewish: The Eppes family were this for the first couple of seasons; the third-season episode "Provenance" established them as non-observant Jews, although in the fifth season, Don starts going to a synagogue and exploring the faith more.
  • Amicable Exes: Don and Liz, after their relationship ends in season four.
  • Amoral Afrikaner: Subverted in one episode. A bank is robbed and a number of safety deposit boxes are emptied. The boxes belong to a number of shady individuals, including a South African mercenary, and are suspected to have contained very incriminated evidence. in the end, the FBI detemines that the whole thing was a Kansas City Shuffle - The Afrikaner mercenary was behind it, but instead of an elaborate heist, it was a plot to ruin the corrupt bank owner who was responsible for the death of the mercenary's brother. The merc turns the evidence over to the FBI and gives the stolen money to his brother's favorite charities.
  • Analogy Backfire: The Director of the Los Angeles Homeland Security Office refuses to shut down his series of anti-terror drills that seem to be the target of a saboteur, even after one attack puts six people in the hospital. When Don and Megan attempt to talk it out with his assistant, this exchange occurs.
    Director's assistant: Stop the drills now, it's like turning the Titanic.
    Megan: The Titanic hit an iceberg!
  • And Starring: Peter MacNicol. In previous seasons, it was Diane Farr that was credited this way.
  • Anti-Hero: Ian Edgerton.
  • Arranged Marriage: The pilot reveals Amita's parents tried to set her up in one of these. Her "fiance" is back in India, while Amita moved to the US when she was little. When asked if she plans to marry him, she replies that she won't, as he doesn't like the guy at all. In a later season, Amita and Charlie start dating. However, Amita admits to Charlie that the fact that he's not Indian will be a problem for her parents. At a dinner with her parents, an old friend of Amita's shows up at the invitation from her parents in an obvious attempt to set them up. Only one problem-the guy is gay. Also, they reveal that, after meeting Charlie face-to-face, they have warmed up to him.
  • As Himself: Penn Jillette of Penn & Teller guests stars in the season five episode "Magic Show'.
    • Buzz Aldrin appears in the third season episode "Killer Chat".
  • Asshole Victim: Frequently. Occasionally paired with Sympathetic Murderer, but in other cases, the victim is just as bad as the killer.
    • One example is in "Killer Chat", involving a Knight Templar Serial Killer going after pedophiles. The climax has the team catch the killer with another pedophile held hostage, and when the victim thanks David after the standoff, David snaps at the pedophile to shut up.
    • The series finale is just a pileup of these. Don loses his gun during an arrest, and it becomes a symbol for people who feel the police aren't protecting them. The three people actually killed are two drug dealers and a chronic drunk driver; there are also near-misses on a man who's been abusing his ex-girlfriend and a bully who's been terrorizing his neighbors.
  • Author Filibuster: In "Money for Nothing", the plot stops dead in its tracks for five minutes so Charlie and a guest star can lecture Colby on the wonders of microcredit.
  • Awesomeness by Analysis:
    • Subverted. The super-brain Charlie Eppes tries, among other things, golf and sniping, and learns that knowing the math simply isn't enough. It requires some kind of instinct or gut feeling to get it right.
    • The episode "Arm in Arms" has one of Charlie's engineering colleagues identify an explosive design flaw in a new model of assault rifle, from just one look at the plans. He's right.
  • Back-to-Back Badasses: Don Eppes and Billy Cooper in "Man Hunt".
  • Backwards-Firing Gun: An inadvertant version occurs in the Season 6 episode "Arm in Arms" due to a design flaw in an automatic weapon: in an attempt to keep the weapon's weight down so it would be easier to carry, the designer made the barrel wall too thin to withstand the heat and pressure buildup that comes from continuous firing, causing the barrel to explode if the gun is in operation for too long. The owner of one of said guns learns this the hard way when his gun literally blows up in his face; he is killed by a piece of shrapnel being driven into his neck by the force of the explosion.
  • Badass Bookworm: As of Season 5, Charlie can SO kick ass. One FBI training course and BAM!, he has a gun.
    • This is subverted. Yes, he can target shoot, but still isn't much good in a real fight.
    Sinclair: It's a lot different when they're shooting back, okay?
    • He also can't do much else. Before his success on the range, he failed miserably at vehicle pursuit, hand-to-hand, and dynamic entry.
  • Bait-and-Switch:
    • "Harvest" starts with a young Indian girl named Santi being discovered hiding in a blood-covered hotel basement, where an underground kidney removal had gone wrong. Santi asks the FBI to find her sister, and they discover a dead South-Asian Jane Doe in a hospital morgue whose blood matches the blood in the hotel basement. When Megan and Amita break the news to Santi using a picture of the body as evidence, she starts crying and muttering "no". That's when Santi reveals that no, this isn't her sister, this is one of her friends, revealing that there were two more girls besides Santi and her sister who were selling their kidneys on the black market at that hotel.
    • In the middle of "Backscatter", a bank manager is accosted by some goons and stuffed into the back of a truck. He starts pleading that he hasn't told the FBI anything... only to look up to see the FBI agents he'd met earlier, who had accosted him to get him out of sight of the Russian mob, who they figured out are blackmailing him.
    • The first half of "Jack of All Trades" has Agent McGowan, who is investigating Charlie and Don during the former's appeal to regain his security clearance, recommending to the decision board that Charlie be rejected and disciplinary action brought up against Don for his more maverick tactics. When the decision is finally made, it turns out that the board disagreed with McGowan and reinstated Charlie's clearance.
  • Bait-and-Switch Tyrant: Mildred Finch in Season 3, as the new division chair of Charlie's department. She initially starts off getting on Charlie, Larry and Amita's cases for a number of issues, but provides insightful expertise in several FBI cases and soon warms up to the group (even dating Alan for a spell).
  • Bald, Black Leader Guy: David Sinclair. Although not technically a leader, he is Don's second-in-command.
    • Don gives him the lead on a few projects, and he also becomes the head of the unit when Don is injured in "The Fifth Man".
  • Batman Gambit: Charlie proved to be pretty good at this in episodes such as "Prime Suspect" and "Primacy". His strategies for trapping criminals include working out their plan so he could predict their course of action, and setting everything up so that to the criminal it seems everything is going according to plan, up until the point the trap is sprung.
    • One example can be found in "Backscatter". With the bank manager being held hostage by a Russian mob hacker who's plundering his systems, he's able to get a look at the hacker's phone and send the number to the FBI. Charlie then calls the hacker to threaten him, leading the hacker to call his boss to ask what he should do next, thereby leading the FBI right to the boss.
  • Bavarian Fire Drill: The fifth season's "Jack of All Trades" features a criminal who is basically a master of this. He can fake his way into any job simply by turning up the charm. When he's finally captured for the first time, he escapes from jail by pretending to be an attorney.
  • Be as Unhelpful as Possible: Averted in the episode "Tabu", when a rich father finds his Paris Hilton Captain Ersatz daughter has decided to go all Patty Hearst. He rushes into the station, takes on look at the TV paused on a shot of his daughter, and says he'll do anything he can to help the police. When the FBI Agent remarks that he's being remarkably helpful, he says that the sooner they get his daughter home safe, the sooner he can prepare a defense.
  • Be Careful What You Wish For: Alan's side plot in "Sneakerhead" has him taking on Charlie and Larry's lab as a class to get his lab credits at CalSci. Little did he know that the class in this case requires manual labor.
  • Beeping Computers: Most user interfaces seem to make an unusual amount of beeping, whining, and chirps as the user scrolls and clicks.
  • Believing Their Own Lies: The Art of Reckoning had a mob killer who wanted to make a confession, but while he passed the polygraph and even an MRI scan, the confession didn't match the facts. It turned out he'd been so horrified by the crime (which he hadn't even been able to commit) that he'd combined it in his head with a much cleaner kill from a different occasion, and genuinely believed that was what happened.
  • Berserk Button: Threatening or hurting Charlie is a surefire way to piss off Don.
  • Beta Couple: Larry and Megan.
  • Big Brother Instinct:
    • Don towards Charlie. Amusingly, big brother Don also works for "Big Brother". But then in this case, Big Brother is also your friend.
      • As a frequent consultant for the NSA (National Security Agency), Charlie works for "Big Brother" as well.
      • Don also acts like a big brother to the entire team. And the other members of the team often treat Charlie like a little brother.
    • In “Robin Hood”, the perp’s brother was indirectly killed by an arson plot masterminded by a corrupt bank president who ran a bank with seedy customers. The perp proceeded to avenge his brother by robbing the bank to expose the president’s misdeeds.
  • Big Disaster Plot: Thirty-Six Hours, which has the team dealing with a train accident.
  • Bland-Name Product: CalSci to Caltech. Though the latter is actually an inspiration.
  • Bollywood Nerd: Amita, who is of Indian descent and a computer genius.
  • Brains and Brawn: The two Eppes brothers, with Charlie being the brains and Don being the brawn.
  • Brief Accent Imitation: In "Bettor or Worse", David pretends to be a package delivery man with a Caribbean accent to get a suspect's father to open the door to his house. This way, the FBI can get him outside so they don't accidentally hurt him while they raid his house to search for the suspect.
  • Buffy Speak: Sometimes used when describing Charlie's equations.
    Megan: Well, there's always Charlie's inequality... bounding... thing.
    Colby: There is always Charlie's "inequality bounding thing".
  • Call-Back: Several.
    • "End Game" and "Arrow of Time" get special mentions for this. Both episodes were call-backs to earlier episodes, but unlike the standard two-parter, it wasn't consecutive. "End Game" is a half a season after the setup episode "Thirteen", and "Arrow of Time" is a full two seasons after "Spree/Two Daughters".
    • Fifth-season episode "Disturbed" uses an equation to track down a serial killer, the very same one used in the first episode "Pilot". David even remembers it and is the one to explain the math.
    • At the end of "Growin' Up", Nikki and Colby remind David about one more piece of paperwork that needs catching up: his physical training. They bring out one of the counterfeit Primer sneakers from the "Sneakerhead" episode the season before.
  • Calling the Old Man Out:
    • Megan does this at one point to a millionaire who acts incredibly cold and distant towards his own daughter, though it is more of a Freudian Excuse due to problems with her own father.
    • Don's not above doing this to powerful people if he thinks they deserve it.
  • Can't Kill You, Still Need You: Referenced in one episode when an escaped prisoner kidnaps the family of the man he blames for his downfall, the team initially assumes his intention is to lure the man to him so he can kill him, but Charlie later determines that he's actually trying to capture him alive (because he believes the man has valuable information he wants). This ultimately plays a critical role in their handling of the situation.
  • Can't Stay Normal: After Charlie's security clearance is revoked at the end of season 4, he has a chance to return his normal life of academia. But he keeps getting pulled into cases, and even begins seeking out crime to solve by consulting for the LAPD, and eventually admits that he's bitten by the crime-solving bug.
  • Catchphrase: "Everything is numbers." Or, perhaps, "everything is numb3rs."
  • The Cameo: The season 2 episode "Dark Matter" features well-known Broadway actress Marin Mazzie as the mother of a suspect. She appears in one scene and has only two lines.
  • Celebrity Paradox: At the end of Season 3 Episode 7, Alan tries to cheer up Don, who has just revealed to his dad and brother that his girlfriend had dumped him a week prior, by finding something fun to watch on TV. What we hear from the TV is the theme from the 70's sitcom Taxi. Alan is played by Judd Hirsch, who was the main character on Taxi.
  • Cell Phones Are Useless:
    • In one episode, Don tries to call another agent to warn her that there's an assassination plot in progress on the witness she's getting out of prison. He can't get through because there's no cell service in the prison. Justified in that there's a pretty good reason for a prison to cut off cell phone reception; they would want to make sure that even if an inmate somehow got access to a phone, they wouldn't be able to use it.
    • In another episode, a kidnapping occurs and the agents only have one hour to save the kid (the episode takes place in a near-Real Time, as well) and could really use Don's help as team leader. Alas, the B0plot is that Don is in a Bureau-mandated psych session courtesy of being involved in a shooting in a prior episode and the psychiatrist ordered Don to turn off the phone. Don only finds out something happened once he returns to the office in the episode's denouement. (In a later episode, the audience learns that Don's psychiatrist has learned of this incident and no longer makes him turn off his phone.
  • Character Death: Dwayne Carter and Mason Lancer in the season four episode "Trust Metric".
    • Adam McKnight in the second episode.
  • Character Development: A very good amount of it, and not always in predictable directions (lookin' at you, Fleinhardt). Probably more so than most other Police Procedural shows.
  • Character Title:
    • Sniper Zero.
    • Charlie Don't Surf.
  • Chekhov's Gift: In "Checkmate", Don is reuniting with his Old Flame Robin while the latter is in FBI protective custody, and gives her a hairclip as a memento of their old relationship. Later in the episode, a Professional Killer is pursuing Robin, but Don uses a tracker hidden in the hairclip to catch up with them just in time.
  • CIA Evil, FBI Good: Mostly absent, even the NSA group that shows up is mostly on the level. However, there is the storyline involving CIA mind control experiments.
  • *Click* Hello: Cold Sniper Ian Edgerton has done this to perps several times throughout the series.
  • Content Warnings: Season 5 Episode 8 "Thirty-Six Hours" deals with a train derailment. It was written and filmed before the tragic Metrolink crash in Chatsworth, CA but was shown after. David Krumholtz gives a content warning that establishes the episode was written and filmed before the tragedy and gives a warning so those who might find the story disturbing can make an informed decision.
  • Cloud Cuckoolander: Dr. Larry Fleinhardt. At one point, he eats nothing but white food.
  • Cloning Blues: The "kidnapped" girl in the Hydra episode.
  • Cold Sniper: Agent Edgerton.
  • Connect the Deaths: Practically every episode, but in one of the early episodes, Charlie develops an algorithm which, based on the inherent human inability to produce random numbers/circumstances, uses a map with pushpins to find where the next murder will/would have occurred.
  • Conspiracy Theorist:
    • One shows up in "Calculated Risk", intent on seeking the truth behind the financial collapse of a big company. He's enough of a paranoiac to disbelieve that the team are real FBI agents when they confront him.
    • Roy McGill (played by Josh Gad), is a specialist on conspiracy theories and an amateur police consultant, who assists the FBI on a couple of cases.
  • Continuity Nod: One episode mentioned a gang called the 18th Street Mexicali, a rival of the gang one of the suspects belonged to. Two episodes later, the gang is mentioned again as a gang that a record-label executive—and the father of the kid kidnapped in the episode—is connected to.
  • Contrived Coincidence:
    • In "Vector", the FBI is called in by the CDC to help investigate a viral outbreak (given the possibility that it may have been an act of bioterrorism). Don wants to bring Charlie, but the CDC insists on using their own mathematical consultant who has the proper clearance. Naturally, the CDC consultant turns out to be Charlie.
    • The case in "One Hour" is this to some extent. The team gets a case while Don's at a therapy session with his phone off, and it just happens to be one with an incredibly short deadline, so much so that the case is fully resolved and wrapped up by the time Don shows up, when many FBI cases require days if not weeks of investigation.
    • In Season 5 Episode 7, a family friend of the Eppes asks Don to look into his surfer son's death, ruled an accident. Don looks over the Park Ranger investigation into said accident at his desk and thinks the investigation was pretty thorough as Colby walks by and recognizes Don's Surfer friend. It is Colby, an Idaho farmboy, who realizes the death was murder because he just happens to be a hardcore surfing fan and notices a detail the park rangers missed.
  • Cop and Scientist: Cop and mathematician, but otherwise fits the trope.
  • Couch Gag: Each episode opens with a grid-patterned screen, each quadrant of which displays the number of something—suspects, dollars, crimes per day, people, whatever—relevant to its plot.
  • Covert Distress Code: At the beginning of season 5, new girl Nikki goes undercover to catch a group of people kidnapping ATM users and is given the distress code "Mexico" to use if the operation starts to go south. It does, but she's too stubborn to use the word, believing that she can salvage the operation on her own. Don berates her for this later and assigns her to answering telephones.
    • "Mexico" is actually David and Colby's long-time covert distress code; each of them uses it once successfully (Colby in "Chinese Box", David in "Ultimatum") when the other is in a hostage situation, to warn each other that a hard entry is imminent.
  • CPR: Clean, Pretty, Reliable: "Trust Metric" plays with this, with David Sinclair performing CPR on Colby Granger after Colby is injected with potassium chloride. However, very little of the process is actually shown in the episode before the scene cuts away, so the trope, whether subverted or played straight, is pretty much avoided (although the "reliable" bit seems to hold, since Colby lives.)
  • Crime After Crime: The perpetrator of "Calculated Risk". Frustrated that his father isn't giving him respect at the family business, he embezzled around $300 million from the company, authored a scam to cover his tracks that possibly brought the whole company down, and then murdered the CFO when she started digging too deeply.
  • Criminal Mind Games: The episode "The Janus List" has a character who, in essence, does this for its own sake. He knows he's dying and wants to hand off his life's work, the eponymous list, to Charlie, but only if Charlie is worthy of it. So he hides the information behind a series of complicated codes and puzzles, which are in essence a test; if Charlie is able to get through all of the layers to access the list, then he's passed the test and proven himself worthy. He does, although one of the pieces ends up being figured out by Don.
    • Lots of episodes do this. Usually the clues require advanced mathematics to unravel, since the show's Aesop is that "Math is useful and mathematicians are like superheroes—with math."
  • Cult Defector: CBI Agent Willons from the episode "Nine Wives" grew up in the cult at the center of the episode. She escaped at the age of nineteen when her cult-assigned husband died.
  • Culture Justifies Anything: The villain of "Trouble in Chinatown" tries to make this argument for ghost brides, but given he's trying to force the issue by murdering undocumented Chinese women workers to give dead Chinese bachelors wives in death, no-one buys his argument, especially not the Chinese-American ICE agent with the team, who pulls a Shut Up, Hannibal! by shouting "Shame on you!" at him.
  • Damn You, Muscle Memory!: In-Universe example in "Primacy", where the FBI try to nab a player who's after an in-game MacGuffin with an accompanying million-dollar cash prize, by creating a fake game server and letting him win the fake MacGuffin. The plan goes awry when Amita, who's played the game since university, accidentally kills the target's avatar and apparently wins the MacGuffin herself, making her a target.
  • Dark and Troubled Past: The brothers are mostly spared this (aside from losing their mom to cancer) but other characters are not so lucky.
    • Megan Reeves literally disappointed her father by being born female (she was his last chance to have a son), and she spent years trying to get his attention, first by positive means and then by acting out, until she finally ran away at 16.
    • David Sinclair grew up in a gang-ridden neighborhood, losing one of his best friends to gun violence when he was in high school, which another best friend was unjustly imprisoned for. He also says at one point that his father died when he was about 14.
    • Colby Granger lost his father in a single-car wreck when he was 15; the cause of the wreck was never determined, but Colby always suspected it might have been a suicide, as his father had recently lost his job and was devastated. And that's not even getting into his time in the military, where he saw way more than his share of trauma.
    • Liz Warner's early life is never discussed, but she does say at one point that she had been pregnant in college and miscarried, and that her friends were so insensitive to her about it that she never spoke to them again.
    • Nikki Bettancourt's past is also not really explored, but we do know that early in her career, she was dumped into undercover work unprepared and one of the targets tried to rape her. The way she plays it off as no big deal also suggests she might have more (ultimately unexplored) trauma in her past.
  • Dead Man Writing: "Undercurrents" has one from an Intrepid Reporter, who went undercover into the Chinese human trafficking trade to get an inside scoop, only to have her body wash up on the beach when she was dumped overboard. Charlie gets the voice message from her when he calls an encoded phone number tattooed on her foot.
  • Deadpan Snarker:
    • Colby can be this at times.
    • Megan Reeves is also this.
    • Nikki does this as well, with David being the usual target.
  • Dead Person Impersonation: In one episode, David thinks that Ron Allen, a supposed witness to burglary, isn't on the up-and-up, so he runs a deep background check and finds that the real Ron Allen died in infancy. They eventually discover that he'd been pulling this scam with different identities at different schools for years, stealing things from each school as he went along.
  • Decoy Damsel: One shows up in "Tabu". At first she appears to be kidnapped by an environmental gang as leverage against her businessman father, but then she starts shooting up the FBI with the gang and it's revealed that she co-opted the gang as part of a giant tantrum against her father.
  • Defensive Feint Trap: Used in the episode Assassin and discussed with a chess analogy.
  • Deliberate Injury Gambit: The climax of the pilot episode has Don holding the perp at gunpoint, except that he has David at knifepoint as a hostage. When the perp is suddenly distracted, David pulls the knife away to give Don a clear shot, even if it means gashing his wrist in the process.
  • Disability Alibi: In “Traffic", somebody is attacking drivers on the freeway with various weapons, which has resulted in several injuries and a few deaths. The FBI figures out that the culprit is someone who's received brain damage from a car accident that made it difficult for them to control their anger impulses, and they find one suspect that fit this profile. However, it turns out that the same accident that brain-damaged the suspect also left him with a non-functional hand and a barely-functional leg (either as a further result of the brain damage or from other injuries he sustained), meaning that he's not physically capable of using any of the weapons involved in the attacks. That, combined with finding no weapon evidence at his house, exonerates him of any suspicion.
  • Disproportionate Retribution: The kindly rec center owner who set off more than a half-dozen "chain reaction" gang shootings after a stray bullet killed his son, resulting in the deaths of hundreds of people, including innocent bystanders and children. Unsurprisingly, he's Driven to Suicide.
  • Distinction Without a Difference: After Nikki screws up on an assignment, Don assigns her to the telephones as punishment and she asks David how long she'll be in hot water for. David says that pre-therapy Don would've kept her there for 3 months, post-therapy Don should keep her there for 10-11 weeks.
  • The Dog Was the Mastermind:
    • In "Structural Corruption", the mastermind behind the defective building cover-up turns out to be the building owner's secretary, who he was having an affair with. She shortchanged her boss by hiring substandard labor and pocketing the difference, because he wouldn't divorce his wife for her.
    • In "Sacrifice", the killer is Scott, the victim's assistant, who was horrified enough at the implications of his boss's research to kill him.
    • In "Where Credit's Due", the killer (and original author of the script for a premiering movie) is the first victim's assistant and housesitter, Tyson.
  • Do Not Call Me "Paul": Recurring character Dr. Mildred Finch, who only wants to be called "Millie". She does not at all like the name "Mildred" (She tries to explain why once, but she's drunk at the time and can't stay on topic long enough to make sense), and she doesn't like to use her professional title either, at least not with people she sees on a regular basis.
  • Double Reverse Quadruple Agent: In "The Janus List", Ashby is said to have been this.
    Colby: By the time MI-6 cut him loose, nobody knew which side he was playing for.
    • Colby edges into this too in "Trust Metric". There comes a point when Don, Megan, and David can't even agree with each other about who Colby is and what he's up to. They do figure it out eventually.
  • Dramatic Drop:
    • In an early episode, Charlie is making a sandwich when he sees a news report on TV saying that FBI Agents are in a firefight with bank robbers; we see the knife he was holding drop to the counter as Charlie realizes that his brother Don is among the agents on the scene.
  • Early Installment Weirdness: In the pilot, the viewer's first introduction to Alan is him playing with a pet bird in a cage. The bird disappears by the second episode, with a fish tank ultimately appearing in its place.
  • E = MC Hammer: Averted. The network actually hired professors to teach Krumholtz the real math he needed to know.
  • Empty Cop Threat: Not every episode, but on occasion.
    • Referenced in the first episode of season 2, where ex-military New Meat Colby tries to intimidate an entire gang and it's falls to David to defuse the situation. David chastises Colby later for "selling wolf tickets".
    • In the episode "Toxic", a private security contractor was found going through the files of a journalist the FBI was visiting. After confirming his credentials, and after the journalist declined to press charges, Sinclair let the contractor off with a warning that if they ever caught him near their investigation again, he would charge him with obstruction of justice personally. Later on, the contractor was seen about to snipe a witness to their case, but Edgerton gets the drop on him.
    • Another episode uses the trope: A man hires private security to find his stolen loot. The FBI is also on the case as two people were kidnapped during the theft. The private security guys barge in as the FBI is about to arrest the kidnappers, which allows them to escape. Don immediately has both men arrested as an accessory to the kidnappers, and warns their employer that if he sees any more of his employees following FBI agents around, he'll have him arrested under the same charges.
  • Enhance Button: A first season episode deconstructs this trope. They are able to "zoom in" on a poor-resolution image, but Charlie and Amita and Amita explain that what they're seeing isn't actually information contained in the original image, but rather a predictive tool that extrapolates from the existing data to fill in the missing information as best it can.
  • Entitled Bastard: One shows up in "Money For Nothing", as an investor who bought a large amount of Zambian debt for pennies on the dollar demands that the relief money should be given to him and even hires private security to track it down after it's stolen, resulting in at least one missed opportunity for the FBI because the private security guys get in the way. He changes his mind in the end and agrees to settle for the (much lower) amount that he paid to buy the debt rather than continue to demand payment in full.
  • Epic Fail:
    • One episode has a suspect flee from the Feds in the middle of his shower, and tries to carjack two women. By the time David and Colby catch up, the women are kicking the crap out of him.
    • In the episode featuring the hacker on the run from various criminal groups, the Israeli hacker/arms-dealer gets cornered by an FBI agent while said Israeli hacker's muscle is elsewhere. The hacker makes a break for the glass window—but does not expect for the break to fail so spectacularly, as the hacker's body (appropriate for his specialty, and thus not made like a linebacker's) bounces off the window not once, not twice, but three times. He is caught, obviously, no doubt wondering why the breakaway glass didn't break away, like in the movies.
  • Et Tu, Brute?:
    • The team is visibly crushed when Colby is revealed to be a double agent for the Chinese, especially David. After things are cleared up, their relationship is rocky for several episodes before they finally get it together again.
    • Lieutenant Walker is furious when he learns that one of his fellow cops, a narcotics officer, was so intent on clearing the streets of drug dealers that he secretly collaborated with a gang member to clear rival stash houses, organised the informant to go down in a raid when he wanted to come forward, and even killed the officer that pulled the trigger when he got suspicious and decided to go to Internal Affairs. Especially since he helped raise his murdered colleague's son afterward.
    • Don takes it hard when he finds out that his FBI mentor turned out to be a Dirty Cop, especially when he had to shoot him.
  • "Eureka!" Moment: Charlie, all the time, mostly highlighted by scenes of mathematical analogies and formulas flickering past his eyes.
    • Amita does it while Charlie is otherwise occupied in "Checkmate", leaving a bemused Larry to wonder, "What is it about this office?"
    • Larry gets one too, in "All's Fair". It being Larry, it's a somewhat literal interpretation.
    • Don gets one in "The Janus List"; Charlie, who's not used to being on that side of it, is both amazed and somewhat taken aback.
      Charlie: Is that the face I make when I...?
  • Everybody Hates Mathematics: Played with, inverted, and subverted. Several characters, including lead Charlie Eppes, love math, and those who don't love math are dependent on those who do.
    • Hell, by the fifth and sixth seasons, some of the FBI actually explain the math, with Charlie grinning like a proud teacher.
  • Everybody Lives: Has a few in the later seasons:
    • "Chinese Box" has only an attempted murder; the intended victim gets a few non-lethal gunshot wounds.
    • In "Power", the team is chasing a serial rapist rather than a killer.
    • "Jacked" has a particularly clever variation: the FBI witnesses an apparent murder via hidden camera, but it turns out to be staged.
    • Similarly, in "Hydra", a non-custodial mother claims to have killed her daughter as the cops were closing in. She eventually admits that she was lying: her daughter was actually a clone, and her "father", the custodial parent, treated her as nothing more than a scientific specimen, so the mother tried to fake the girl's death so the police and the researchers would stop looking for the child, giving her a chance to disappear into a normal life.
  • Evil Counterpart: Quite a few episodes had the criminal being a genius Charlie could relate to.
  • Expy: Bill Nye. Played by Bill Nye.
    • Another example would be the villain of the Season 5 finale: a very intelligent cult leader who has a bit of a god complex and whose followers are only women. He's played by James Callis. There are few differences.
  • Explain, Explain... Oh, Crap!: The deduction of motive in the episode "Dreamland". After finding out a company's project was going awry due to the R&D process not going fast enough, Charlie asks his CalSci engineering colleague "Otto-bahn" if he thinks he could complete the project in two weeks given the funding. Otto-bahn eagerly agrees that it's possible if they got enough manpower and took some risks, before realizing that that exact mindset was what led the company's people to volunteer themselves as test subjects and got them killed.
  • Explosive Stupidity:
    • The arsonist villain of "Scorched" tries to hold off the FBI with a container of white phosphorus. He bangs his head while trying to escape through a pipe and drops the container, incinerating him alive.
    • David and Colby corner a shotgun-wielding suspect in a garage that was recently used to make bombs, and the suspect firing his weapon causes the residue to explode and kill him. However, he clearly did recognize the danger posed by explosive residue in the air (the earlier parts of the episode had him getting his associates to smoke outside), so his mistake is more likely the result of panic, or it might even have been an intentional Suicide Attack.
  • External Combustion: Takes out potential witnesses in "Democracy" and "Pay to Play"; another almost gets killed in "Blowback," but the bomb goes off too soon.
  • Extreme Graphical Representation: Justified in one episode, where a computer scientist hides the fact that his artificial intelligence computer is a fraud by creating a very elaborate and impressive-looking computer room and interface.
  • Extremely Protective Child: Joel, the grandson of Holocaust survivor Erika Hellman, is incredibly protective of his grandmother, especially when it comes to her quest to win back the Pissaro painting that had belonged to her father before the Nazis stole it when they sent them to the death camps.
  • Extremely Short Timespan: Most episodes takes place over the course of days if not weeks, but there are a few exceptions.
    • "One Hour" is probably the shortest. While it doesn't literally cover only an hour, the first scene takes place in the early morning and the episode wraps up before lunch. It's short enough that Don misses the entire thing because he's at a therapy appointment.
    • Between the lack of night scenes and the timeline of events, "Trust Metric" appears to take place over a single day, though this is never made explicit.
    • "Jacked" is set around a four-hour bus hostage crisis.
  • Failed a Spot Check: The villain of "Primacy". For all that he divines about Amita (whom he's targeting for winning a MacGuffin in an online game), including her name, address, workplace, etc., he somehow fails to notice that she often works closely with the FBI, and is thus taken off guard when his kidnapping attempt turns into an FBI trap for him.
  • Fakin' MacGuffin:
    • Where the MacGuffin in question is a math equation. A mathematician had his daughter kidnapped so that his ground-breaking solution to the Riemann hypotheis can be used as a codebreaking tool. When Charlie finds out that his solution will not work, Don comes up with the idea of giving them a fake solution that will open an electronic door that the FBI would set up for them that allows them to track down their location, allowing the FBI to raid it, arrest the criminals, and save his daughter.
  • Fake Defector: Colby Granger turns out to have been a triple agent for several years. This causes a fair bit of drama and angst, since the rest of the cast find out about the "defector" part well before they find out about the "fake".
  • Faked Kidnapping:
    • "Magic Show" involves a magician with a record of faking disappearances in her act and even specifically inviting law enforcement officers to her show to drum up publicity after she disappears "for real" onstage. Then it all goes awry when her equipment malfunctions and she is killed by her trick.
  • Fatal Family Photo:
    • "Burn Rate" starts with a Fatal Family Montage; the initial Victim of the Week is seen enjoying a moment with his wife, son and daughter before heading to work. When he receives a letter bomb, the debris is seen raining on a family photo.
    • "Scan Man" starts with an FBI arrest gone bad and one of the agents gunned down. His last moments were him reaching for his fallen helmet, in which was a picture of his family.
  • FBI Agent: Half the main cast is one. For the whole series, Special Agents Don Eppes and David Sinclair. For some seasons, Special Agents Terri Lake (Season 1), Colby Granger (Seasons 2-6) Megan Reeves (Seasons 2-4), Liz Warner (3-6) and Nikki Betancourt (5-6), plus frequent guest star Ian Edgerton.
  • Feed the Mole: The strategy used in the episode "Assassin".
  • Finding Judas: In the first season episode "Vector", the team is investigating several deaths caused by a disease thought to be wiped out. In the end, the culprit ends up being one of the scientists responsible for looking after the remaining strains of the virus. He thinks that another outbreak was inevitable, and by infecting a few people, it would force doctors to find a cure and prevent an epidemic in the future. In fact, the finds him lighting candles at a church to pay respect to the victims.
  • First-Person Perspective: In later seasons the show used gun barrel perspective as the FBI agents performed operations intercut with more regular footage.
  • Five-Man Band:
  • Fixing the Game: More than a few episodes involve games that prove to be influenced by external, illegal forces. Examples include horse racing in "Longshot", MMA match rankings in "Contender" and even Russian Roulette in "7 Men Out".
  • Foreshadowing: Before Colby was revealed to be a Chinese spy:
    Just the two?
    Just the two. Only one we need alive is the reporter.
    • The previous episode, "Money For Nothing", also contains a conversation between Don and Colby about loyalty that's rather prophetic.
      Don: How well does anyone know who they're working with?
      Colby: The way I see it, you got a team, you got to trust 'em. That's just the way it works.
    • Larry remarks in "Sniper Zero" that if he ever got a chance to go to outer space he wouldn't hesitate at the opportunity. In season three, guess what he gets to do.
  • Flash Mob Cover Up: In the episode "Animal Rights", the villain organized a flashmob ahead of time to distract the authorities at a key moment.
  • Former Friends Photo: Colby is shown to keep several pictures in his desk from his days in the army. Among them is a picture of him and Dwayne Carter before Carter turned traitor.
  • Found the Killer, Lost the Murderer: In one episode, a hidden camera catches an image of the man responsible for planting a bomb in a meeting, and another witness recognizes him and gives them a name. The man in question is killed in a shootout with the FBI, and when they search his apartment, they find a check dated just before the bombing. They realize someone paid him off to do it, and with the bomber dead, they don't have any leads. Luckily, Charlie comes up with something.
  • Friendly Enemy: Charlie Eppes and Marshall Penfield in the fifth season story "Frienemies".
  • Friendly Sniper: Agent Ian Edgerton oscilates between a mild version of this and Cold Sniper depending on the episode. It might be done purposely, since it is known he likes messing with people's heads. Especially Charlie and the team's.
  • Fun T-Shirt: Charlie is frequently wearing 'Nerd' shirts, including one with the pi symbol made up with the digits of pi.
  • Gambler's Fallacy: Invoked in the pilot, when Don, watching a baseball game with his father, comments that a batter is "due" a big play after going four games without a hit. Charlie is quick to refute this theory, saying that there's "no statistical evidence for a batter being 'due'," but the player does in fact get a big hit. It turns out, however, that Don is yanking Charlie's chain a bit; what they're watching is not a live game but a tape of a game from the day before, and Don, having read a recap in the paper, already knew what was going to happen.
  • The Gambling Addict:
    • In the episode "Bettor or Worse", it's revealed that the victim who had his wife and daughter kidnapped is one, and he arranged the kidnapping of his family and the robbing of his own jewelry store to get the insurance to pay off his gambling debts.
    • The episode "Double Down" reveals that Larry was once one, and although he got out of the habit, one of his fellows wasn't as lucky. Said fellow got some of his students into the card-counting realm of cheating casinos, and the situation ended with two of them dead and another one in jail. Larry is disgusted at what his old friend got his students into.
  • Game of Nerds:
    • Dr. Fleinhardt is a Dodgers fan.
    • There is also another nerdy character that plays Fantasy Baseball, Oswald Kittner, who's played by Jay Baruchel, who is a real-life friend of David Krumholtz, according to the DVD commentary on that episode.
    • Charlie is also somewhat implied to be a fan, as he calls it "the most statistically driven sport in the world" with a note of pride in "Sacrifice" note  and chuckles in agreement when Alan jokes that you don't need statistics to predict that The Dodgers aren't going to win the pennant that year.
  • Gangsta Style: One episode showed two gangsters firing their guns this way. They missed.
  • Genocide Survivor: An elderly Jewish-Holocaust survivor named Erika Hellman is a one-shot character in "Provenance".
  • Gentleman and a Scholar: Charlie and Larry in different ways. Amita, too.
  • Good Parents: Alan.
    • Margaret Eppes, too, judging by the way the entire surviving Eppes clan talks about her.
  • Good with Numbers: Charlie, of course.
  • Gracefully Demoted: In Don's backstory, he was the Special Agent in Charge of the FBI Field Office in Albuquerque but took a demotion when his mother got sick from cancer so he could transfer to the LA office to be nearby her and his other family.
  • Hair-Trigger Explosive: Subverted. The perpetrator of "Protest" tries to hold off the FBI with a stick full of blasting gel, known to be much more powerful than dynamite, but is tackled because Colby knows that blasting gel might be more powerful, but it's also more stable, and won't go off from simply being dropped.
  • He Had a Name: The third episode had a rare example of the perpetrator remembering the names of all his victims, who died as the result of a virus he unleashed with the endgame of trying to save many more lives. He was on his way to light candles for them in a church when he was caught.
  • Heroic BSoD:
    • Charlie goes through a lot of these.
      • He goes through one in the very second episode when Don is placed in a life-threatening situation because he followed Charlie's advice:
        Charlie: [frantically] The fact that you survived is an anomaly and is unlikely to be the result of another such encounter.
      • He tries to work himself into a safe space by trying to solve the famously difficult P vs. NP problem. Don isn't happy about this since Charlie buried himself in the exact same problem after their mother got cancer, and it takes a while to coax him out of it.
      • He gets another one in "Rampage" due to the trauma from the shooting attack at the FBI (especially since he almost got caught in the crossfire), to the point where he refuses to go back there for a few days afterward.
      • He goes into worse ones in Season Five when Don is stabbed and nearly dies and three episodes later when Amita is kidnapped because a terrorist wants to use her for her computer skills.
    • It seems to run in the family. Don is prone to getting stuck in his own head when a case hits too close to home ("Trust Metric", "Arrow of Time", "Angels and Devils"). Not to mention arranging for Edgerton to beat up a suspect in the Season 3 opener.
      • In an earlier episode, "Rampage", Don had admitted to Charlie that he's able to cope while the situation is active, but runs into trouble when it slows down enough for him to think.
    • The mathematician in "Prime Suspect" has one when his solution to Riemann's hypothesis, which his daughter was kidnapped for, turns out to have a critical flaw that renders it incorrect, and thus worthless to trade for his daughter's life. Fortunately, Don and Charlie comes up with the idea of giving them that fake solution and rigging it to open a fake FBI electronic door, thus revealing their hideout's location and allowing the FBI to raid it and successfully save his daughter.
    • Also in "Rampage", Colby takes it pretty hard when it turns out that his bullet was what killed the suspected pedophile during the shooting attack, even after all of the evidence shows that it was an accidental death because the bullet Colby shot through the attacker's shoulder to stop his rampage accidentally landed in the suspect's head so it wouldn't threaten his job at the FBI. Mainly because it reminded him of a similar incident during his Army days when his troop accidentally attacked a British troop mistaking them for Afghan enemies, which resulted in two British soldiers dying.
  • Hero of Another Story: Though he is usually part of the main story, Larry takes a trip into space in Season 3 and spends several months living in the desert in season 6. He never gives more than very fleeting details about those experiences, but they would no doubt be interesting stories in their own right.
    • Megan also goes on special assignment for the latter half of season three (a case of Real Life Writes the Plot, as actress Diane Farr was pregnant). Becomes a bit of a subversion in that she seems to have come away from that feeling that she was more of a villain than a hero during that time.
  • He's Back: In the Season 5 episode "Jack of All Trades", Charlie walks back into the FBI office to applause after his security clearance, which was revoked at the end of Season 4, is reinstated.
  • Heterosexual Life-Partners: David and Colby. At least until they decided to play their Ho Yay for laughs.
  • He Who Fights Monsters:
    • In "Dark Matter", the mastermind of the school shooting does have a sympathetic motive (she was raped at a party and wants to get revenge on the people involved), but the fact that their way of doing so also put hundreds of school kids who had nothing to do with what happened in harm's way pretty well cancels out any sympathy they might have had.
    • This is discussed heavily in "Killer Chat", since it's about a Knight Templar Serial Killer who is murdering child molesters.
      Don: [while interviewing a teenaged suspect] Look, it makes sense you'd want to get back at people like that, with what happened to your sister. It's normal, it's natural; I would, too. But that makes you just like them, right?
      [suspect nods his head "yes"]
      Don: Is that the person you want to be?
      [suspect shakes his head "no"]
  • Hidden Depths: Colby speaks Spanish, which helped them on a case that had missing Spanish girls.
  • Hollywood Nerd: All over the place, but Charlie is the most prominent.
  • Hot Teacher: Amita is young, brilliant, and attractive, and typically wears flattering casual clothes while teaching.
  • How We Got Here: "Blowback" begins with a montage of scenes from late in the episode, then skips back to the beginning of the case.
  • Idiot Ball: The FBI has an unlimited supply of those.
    • YMMV on this. Charlie is more of a face for the real life technicians and consultants that would really be used by the FBI. The techniques tend to be rather standard, Charlie is just Mr. Exposition about how the techniques work. And having him as a university professor is fancier than an official FBI analyst.
    • One wonders, how often did the FBI catch criminals before Charlie started helping them? An episode illustrates the FBI's helplessness brilliantly. A man is accused of shooting an FBI negotiator during a face-off with the FBI. He flees after saying he's innocent He really is, and the FBI has been hunting him for months. It's repeatedly mentioned that every cop in the county wants to catch the guy, because he's a suspected cop killer. The bullet that killed the officer flew out of his body, and yet, despite the zeal with which the FBI wants to catch the guy and have him condemned, no one tried to find the bullet that killed their officer, if only to reinforce their case against the guy once they catch him. The bullet is lodged in a tree, with a prominent bullet hole, so it's not like finding it is hard (in fact, once the protagonists decide to look for it, they find it in a few hours) The bullet does prove the guy's innocence, but since no cop knew that, it still wouldn't explain why they never tried to look for it.
      • The idiot ball on that one is played with. The thing is, the house was surrounded by police who were intent on watching the house. They knew there was an armed man inside and they were prepared for that man to fire on them. No one expects a drug company to sell him a tainted vaccine, then when the government catches on to the tainted beef to then hire a sniper to frame the man for murdering a hostage negotiator. Every one at the site, faulty witnesses as they may be, would testify to the fact that they were watching the house at the time of the shot and that the armed man was inside. When they are cops at the scene of the crime negotiating with a man who has threatened to shoot them and then someone gets shot, it's kind of justified to think the same man is shooting. Plus, they had the bullet that was inside the negotiator. They just neglected to make sure that the trajectories were right. Probably because they were storming the building and taking him to cover. Later, they do actually just haul the Idiot Ball around. See the next reference for this episode.
      • In the same episode, it's mentioned how surprising it is to the FBI's expert manhunter that the fugitive never tried to leave his home county, despite it being in his best interest to do so and avoid the intense police presence searching for him. The cops repeatedly found the campsite where he stayed, but just after he's just vacated it. Yet it takes Charlie and his math to reveal the obvious: The man's sticking around his home county because he goes to visit his wife once in a while. Said wife still resides in their home, where the shooting took place. That's right. The FBI, and their expert tracker, NEVER considered that a fugitive who remains near his home might be visiting his family on a regular basis.
    • In another episode, they ask an interviewee if she knows anything about pot. After denying it, she mentions that she doesn't know anything about pot farms. They treat it like a Suspiciously Specific Denial. Of course, they do turn out to be right.
    • Garden variety Idiot Ball that seems to occur just about every episode: agents, usually David & Colby, approach a guy to ask him a few questions, identify themselves from about fifty feet away, guy then looks around nervously and bolts in the opposite direction, leading to a foot chase. These are experienced FBI agents? You'd think they'd have learned by now.
    • A more proper Idiot Ball is with Millie's reaction to the consulting that her professors do. Given the government contracts that could bring in, that seems like something that she should encourage.
  • Idiot Savant: Or "Scan Man" in the case of the titular episode. A savant shows up in the episode working for a parcel delivery service, who can identify a parcel's serial number from just a look at its damaged barcode, but is a compulsive hoarder and barely able to talk with others.
  • I'd Tell You, but Then I'd Have to Kill You: Played straight by Charlie in "Assassin" (S02, E05).
  • If Jesus, Then Aliens: This trope seems to crop up with distressing regularity. Every few episodes, Charlie is challenged to move beyond the empirical world to a matter of faith, only the matter of faith in question is something completely outside the normal debate of science vs. religion, and yet Larry's right there urging Charlie to consider that it might possibly be true. After all, even scientists don't pretend that they can know everything, right?
    • More like Larry's just weird that way. If anything, his entire character exists to pointedly avert the Straw Atheist scientist stereotype while other scientists (like Charlie) take a more traditional view.
    • Actually, it's more that Larry is a physicist whose focus is on Quantum Mechanics in subatomic theory where the observation of a particle changes its nature and the reality of a subject of inquiry can be both existent and non-existent concurrently depending on the parameters of study. Hence, he spends most of his time theorizing on things that change when he observes them. Spending a career on that requires an existential trust in both stable and unstable influences that are constantly interchangeable. i.e., he has to have faith in stuff that isn't there because half the time when he finds it is there, it actually isn't.
      • Nonsense, particle physics and quantum theory aren't faith based, nor are they more predisposed to that sort of thinking. That's like saying statisticians are prone to the same thinking because they study systems with probabilistic behaviour. Or, people studying GR are moral relativists because "everything is relative" to them. Or students of nonlinear dynamics have messy houses and don't keep appointments because chaos theory and their subject being about not being able to control outcomes. Etc. Larry seems like a new age 60's hippie that got into physics - kind of reminds me of some (not all) is the early drug chemists that made psychedelics.
      • It may also be the other way around, that Larry was already prone to that kind of existential thinking, and that's what drew him to quantum mechanics, in the same way that, while not everyone who studies relativity is a moral relativist, a moral relativist might be drawn to relativity in the scientific sense.
  • I Hate Past Me: Played for Laughs when Larry returns from his space mission, then walks into his office that is packed wall-to-wall with his old possessions and documents.
    Larry: This... this is obscene! Who is this person that belongs to this mess?!
  • I Have Your Wife: It happens at least once per season, but fortunately the FBI usually intervenes before anybody can get seriously hurt.
    • "Prime Suspect" involves four criminals kidnapping a mathematician's five-year-old daughter because they believe he solved the Riemann hypothesis, which can be used as a master key for virtually any internet encryption, and they're using her to get the solution as ransom.
    • In "Rampage", the man who shot up the FBI office was coerced by a contract killer hired by an arms dealer to get him acquitted from his current trial to do it or else he'll kill his wife and daughter. Rather than kidnap them outright (which would have tipped off the FBI to the real motive behind the attack), the contract killer uses surveillance photos to show the guy how easy it would be to find them and hurt them. It's also played straighter when a critical witness in that arms dealer's case has his family kidnapped by said contract killer.
    • "Backscatter" has some bank employees captured (one of whom is pregnant) by the Russian mob to coerce their boss into letting them access his bank for their robbery.
    • Crystal Hoyle takes the cake on this one in "Spree"; she kidnaps Megan to extort the FBI to let her partner go. It does turn out there was a little more to it than that; in addition to a hostage, she also swiped the agent's credentials to look up some classified information.
    • In "One Hour", a child is kidnapped to extort a ransom from his multi-millionaire father.
    • "Tabu" appears to be another case of a rich parent's child kidnapped for ransom, but it turns out the "victim" was actually the mastermind.
    • In "Chinese Box", David becomes the hostage of a disgruntled former contractor after trading himself for a woman the man had initially taken hostage.
    • In "End Game", a disgraced former Marine captain wants information from one of his subordinates, so he kidnaps the man's father and sister to force him to give it up. The father is killed for trying to fight back, but the FBI manages to rescue the sister and arrest the hostage takers.
    • In "Jacked", a group of criminals hold an entire busload of tourists hostage to extort a ransom from the bus company. It turns out to be mostly illusion.
    • Toyed with but averted in "Hydra". A child's kidnapping is initially presented to the FBI as a ransom abduction, but the case turns out to be much more complicated.
    • The bad guy in "Shadow Markets" threatens his rival's elderly aunt to force the rival to meet him so he can take his revenge.
  • I Just Shot Marvin in the Face: In one episode, a movie star's friends are being blackmailed, and the secret is this trope.
  • "I Know What We Can Do" Cut: In the episode "Backscatter", two bank employees are taken hostage to force their boss to cooperate with an ATM hacking scheme. The team figures it out and confronts him, and he finally agrees to tell them the truth. His description of what's supposed to happen according to the kidnappers is overlaid over video of him playing his part (basically, appearing to go along with the scheme), intermixed with shots of the FBI's behind-the-scenes actions.
  • Illegal Gambling Den: In one episode, the team uncovered a gambling website where patrons can bet on a Russian Roulette-esque Deadly Game. The premise is that a revolver will be loaded with a single bullet and players take turns pulling the gun's trigger while it's pointed at them. The loser is the one who pulls the trigger while the bullet is in the position where the revolver can actually fire it.
  • Informed Flaw: It's mentioned a couple of times in early seasons that Charlie is a terrible speller, such as when he when he gives an eight-letter word for egotistical as "conceted". It doesn't have much effect on the plot, but it does give his family a means of deflating his ego when they switch games from chess to Scrabble.
  • Infraction Distraction: Used as gambits by some criminals.
    • "Rampage" involves a madman breaking into the FBI office and start shooting the place up, allowing an inside man to smuggle out some confidential data during the evacuation to assist in getting an arms dealer acquitted.
    • "Backscatter" involves Don and his family personally targeted by the Russian Mob, preventing them from looking too closely at the bank the mob is trying to plunder of its secure info.
  • Instant Marksman: Just Squeeze Trigger!: Both downplayed and somewhat justified in "Sniper Zero". Charlie's bullet ballistics number-crunching keeps failing to give him the whole picture of how the suspect sniper operates, so he resolves to learn what shooting a gun feels like. After struggling with a rifle at the shooting range for a while, Don gives him a few of the usual pointers: relax his hands, shoot in-between breaths, etc. Charlie's next shot, while not sharpshooter material, is a lot better, and his final prediction on the sniper's nest location is off by only a few feet.
    • Don also points out to Charlie that there's a difference between shooting paper targets and real people. He may primarily be referencing the emotional impact, but the same is true of aiming. (Charlie and David have a similar conversation four seasons later, in which David clearly is referring to marksmanship.)
  • Inspector Javert:
    • Lieutenant Walker becomes this in "End of Watch", where after a badge of a missing rookie cop under his command is found, he's certain that the brother of the man the cop killed is responsible. He is furious when he finds out that the rookie cop was killed by one of his own colleagues who turns out to be Dirty.
    • One shows up in "Burn Rate", believing that a past suspect of a serial bombing case is up to his old tricks. He isn't, and even has to save her from a bomb himself.
    • FBI agent Roger Bloom is this to the conman Kevin Oliver, pursuing him for two years. He eventually admits to Don that it became personal when Oliver stole money from a company owned by Bloom's sister, and wanted to catch him both for vengeance and to retire on a high note, even going so far as to steal more cash from the places Oliver hit to get more of the bureau's attention.
  • Insufferable Genius: Charlie can on occasion be this. Just enough times to give him human faults.
  • Interdisciplinary Sleuth: Charlie solves crimes with mathematics!
  • Interrupted Intimacy: In "Man Hunt," the FBI tracks down one of the escaped felons to his girlfriend's house, and they raid it to make the arrest just as they're in the middle of having sex.
  • It's for a Book: Used by the villains of "Dirty Bomb". They contacted a researcher for a nuclear company for information about a particular radioactive isotope (how to handle it safely and stuff like that), claiming they were doing research for a movie script. Because the series takes place in Los Angeles, the researcher wasn't suspicious until she saw an internal Department Of Energy alert warning that three caskets of the isotope was stolen to make a dirty bomb. She subsequently contacted the FBI, which proves useful in finding the identities of the criminals.
  • It's Personal: Happens quite a bit.
    • 'The Janus List"/"Trust Metric" is one of the biggest examples for the team. Megan put it best:
    Megan: Why are we doing this? We're acting like this is any other case, and it isn't.
    • A close runner up is "Two Daughters", which was a normal case until Megan is taken hostage, then it becomes very, very personal. Though Megan herself doesn't seem to feel that way, despite everything that happens.
    • "Breaking Point" has two separate versions of this around the same case. Colby has this from the beginning, identifying with the victim to the point of obsession, while Don starts off professional, takes it very personally when their antagonist goes after Charlie.
    • Charlie gets the Season Four finale and no less than four separate cases in Season Five (including that season finale as well).
    • A variation occurs with Colby in "Greatest Hits". He clearly Sympathizes with Bloom, but he eventually reveals that it's not so much Bloom himself as the fact that Bloom's situation reminds him of what happened to his father (who he suspects killed himself because of it).
  • I Want Grandkids: Alan takes the proactive approach, giving solid relationship advice to Don and Charlie.
  • I Want You to Meet an Old Friend of Mine:
  • Jack Bauer Interrogation Technique: The episode "Two Daughters" has this technique being pulled on Buck Winters, so that they can find out where his wife, Crystal Hoyle, has taken the kidnapped Megan.
  • Jack the Ripoff: "Sniper Zero" has a spate of sniper killings with hunting rifles. After the news exposure and the news that the killer is still at large, several other disgruntled individuals use hunting rifles as their M.O. of choice. Once they discover that some cases are independent of the spree, they are solved relatively quickly.
  • Jerk Jock: The Jocks who raped Karen in Dark Matter are this.
  • Jurisdiction Friction: Zigzagged. Don's FBI crew has a tendency to work and play well with other agencies; they especially have a good relationship with the local cops. However, as shown in "Brutus" and "Finders Keepers", the CIA and NSA are another story.
  • Just in Time: At the beginning of season 4, Don and his team manage to get to a captured Colby seconds after Lancer sticks the last lethal needle into his chest (but before he pushes the plunger), forcing them to use CPR to revive him.
  • Just Smile and Nod: The FBI gang do this when Charlie explains some very complicated math theories.
    Charlie: Right, no, we have to consider variegated terrain and a considerable time gap. Compensate for the time lag. Add overlapping search spirals to maximize the area covered...
    Edgerton: ...Anyone else following this?
    Granger: Just nod your head and wait for the punchline.
  • Just Like Robin Hood: One shows up in "Robin Hood", natch, who robs a bank known to have customers with seedy connections and gives the proceeds to charity.
  • Kick the Son of a Bitch: "Rampage" starts with the team working on a pedophile case with the suspect in interrogation. Said pedophile becomes a victim of collateral damage and the only fatality when someone else bursts into the office and starts shooting up the place.
  • Killed Off for Real:
    • Trust Metric: Mason Lancer and Dwayne Carter.
  • Knight Templar: Several.
    • The man who lost his son to gang violence, and starts setting off "shooting chains" to cause as many gang member casualties as possible.
    • The woman who had her husband molest their daughter, kills him in revenge, and starts tracking down other pedophiles to torture them, get their confessions, and then murder them to prevent other children from being molested.
    • The man who was a victim of a hit-and-run that went cold, who started assaulting every person he sees responsible for road danger.
  • Knight Templar Big Brother: Don... he has gotten better about it over the years, though.
  • Know When to Fold 'Em: In "Prime Suspect", four criminals kidnap a mathematician's five-year-old daughter because they believe that he solved the the Riemann hypotheis, which can be used as a codebreaking tool to hack through banks' digital encryption and they're using her to get the solution as ransom. When the FBI raids their hiding place and arrests two of them while killing the third in self-defense, the last kidnapper holds a handgun to the kid's head in an attempt to salvage the situation in his favor. Fortunately, Terri manages to subvert the Hostage Situation by pointing her rifle through a window at his head, giving her a way to kill him if he tries to harm the girl or escape. The kidnapper realizes he has no moves left, so he lets the girl go and surrenders.
  • Lady of War: Megan, Liz, and Nikki all fit this trope to varying degrees. Amita has her moments as well.
  • Layman's Terms: Once an episode Charlie or one of his colleagues references an obscure mathematical concept that can be used to help solve a case, then creates an analogy to make it understandable. The team has come to expect them and basically ignore the math and wait for the analogy. See Just Smile and Nod.
    • This predictable behavior is lampshaded in "Brutus" when the agent prompts him for the analogy: "Imagine..."
    • Occasionally inverted by Larry for laughs, who takes everyday situations and complicate it by adding cosmological terms.
  • Letters 2 Numbers: Or, if you prefer, L3tt3rs To Numb3rs. The show also did this in its opening sequence. The names of the actors would slide across the screen to the right as numbers, resolving then into the letters of the actors' names, except for a couple of them, which would remain briefly before then switching over to the letters.
  • Let Off by the Detective: The episode "Robin Hood" involves the robbery of a bank frequented by suspected antiquities smugglers and drug dealers, who are robbed and the proceeds from returning the spoils/retrieving the goods given to charities. When the team finally track down the bandit (who was the brother of a firefighter that died in the arson burning of a homeless services house, orchestrated by the bank manager who wanted to develop the land), they have already arrested the manager for conspiracy of the arson and the arsonist himself, so Don mentions the man's upcoming trip to Venezuela and recommends he stay there for a good long while.
  • Loads and Loads of Characters: While the core duo Don and Charlie, appear in every episode, and characters like Alan, Amita, David, and Colby are almost always present, there's a revolving cast of other characters who are so known to the audience that their appearance is nothing special, but who still don't make it into every episode.
  • Lonely at the Top: In the episode "Sacrifice", Charlie and Larry went to a funeral of one of Larry's colleagues. Larry laments how the man was brilliant and a genius and yet, there was no one else at the funeral except for the two of them.
  • Lonely Funeral: In the first season episode, Sacrifice, Charlie went to a funeral of a colleague of Larry's only to see that Larry was the only one there.
  • Longer-Than-Life Sentence: "Arrow of Time" reveals that Buck Winters from "Spree" received a 250-year sentence for his crimes in that episode. (And then, he breaks out of prison and kills a man, implying that he'll end up getting even more time tacked onto his sentence.)
  • Magical Defibrillator: Averted altogether in the season five episode "The Fifth Man". While in the hospital,Don's heart goes into fibrillation and the defibrillator is used to restore a normal rhythm. You can see the monitor displaying an erratic heartbeat. When he flatlines, they use a syringe filled with a drug to attempt to revive him, not the paddles.
  • Make It Look Like an Accident: A late season five episode, Colby Granger mentions that he believes his father, who died when his truck went off a cliff on a mountain road, may have done this to himself. There's no proof either way, but since there's only one small stretch of that road that doesn't have a guardrail between the road and the cliff, Colby finds it a little suspicious that his father just happened to go off the road in that exact spot, especially given that he had been depressed over losing his job.
    • A couple of earlier episodes involve situations where a criminal tries to eliminate witnesses without being caught by staging accidents (and in one case a suicide), figuring that no one will connect these apparently separate incidents. In both cases, it works until someone makes a connection between the victims, at which point it becomes clear how unlikely it is to be a coincidence that all of these witnesses would happen to die in accidents within a relatively brief time frame.
  • Mama Bear: A dark example in "Killer Chat"; Elaine Tillman found out that her husband molested their daughter (she knew he was a pedophile, but he had promised her he wouldn’t do anything to their children), so she murdered him in revenge. Then she started luring other child molesters to vacant houses under the disguise of a teenaged girl online, torturing them to get their recorded confessions, and then murdering them so no other innocent kid would go through what her daughter went through ever again.
  • Manly Tears: Charlie breaks down in Don's arms when he thinks Amita may have been killed.
  • Married to the Job:
    • This Seems to be the case for a good deal of the cast. David and Colby seem to consider this a badge of honor, or at least an excuse why they aren't in relationships. Nikki meanwhile, while devoted, does try and date. Granted, said relationships don't work out for circumstances (a date bailed because of an unexpected connection and her romance with the sniper was put on hold when he had to serve time.)
  • Maybe Magic, Maybe Mundane:
    • In Hot Shot it's not entirely clear if Alan and Charlie are dreaming or seeing visions of Margaret (JoBeth Williams) but it is treated like they are dreaming.
    • One episode has the Eppes family quarreling about the legitimacy of a psychic, when suddenly a vase in their house breaks for no apparent reason. Alan comments that their mother hated when her family argued.
  • Meaningful Name: Amita Ramanujan. Srinivasa Ramanujan was a very famous mathematician.
  • Measuring the Marigolds: Subverted by Charlie in that he appreciates the beauty of the world, he just sees math as playing a part in that beauty.
    • It's later played straight in "Magic Show", where he finds it hard to appreciate a magic performance since he knows there's always a trick behind it. Amita helps him appreciate the trick itself.
  • Meet the In-Laws: In Pay for Play Charlie goes to meet Amita's parents and he is nervous about it. Things do get awkward but Amita's parents do eventually accept him when they meet him.
  • Misplaced Retribution: The villain of "Judgement Call" has this as their motivation. A detective got killed and his killer caught, but though the jury recommended the death penalty, the judge overruled them and gave him life in prison instead. For years after, the cop killer made numerous appeals for retrials, agonizing the detective's widow with every moment that looked like he'd go free. In the end, through her husband's old contacts, she found a hitman to go after the judge's wife, to make him think about "the next criminal he goes easy on".
  • Minor Crime Reveals Major Plot:
    • "Calculated Risk" has the FBI investigating the murder of the CFO of a company that just went under, but Charlie's analysis reveals that the murderer killed her because she might've found out that he was embezzling money from the company and then authored a scam to cover it up, which may have also brought the company down behind him.
    • "Black Swan": An apparent innocent bystander at the scene of a drug raid flees from the cops, and the FBI discovers that he's involved in a domestic terrorist bombing plot.
    • An Invoked Trope in "Robin Hood"; a high-tech bank robbery turns out to be just one piece in an intricate scheme to expose the misdeeds of the bank's president, as the perp's brother was indirectly killed by an arson plot the bank's president masterminded.
    • "Assassin": While busting a passport forger, the FBI discovers evidence of a plot to murder the last member of an influential South American political family.
    • "Waste Not": A sinkhole suddenly forms underneath an elementary school playground, killing a teacher and injuring several children. During the investigation into why it happened, it's revealed that a construction company has been dumping toxic waste barrels underneath the playgrounds they've built at several low-income schools.
  • Minored In Ass Kicking: Megan Reeves as she may be primarily the psychologist, but she's also a black belt in Krav Maga, and one of the best shots in her entire FBI office. Do not make the mistake of thinking she's soft or won't fight back.
  • Mistaken Age: Charlie was once invited to a bed and breakfast in Santa Monica after publishing his first paper. Unfortunately, he was fourteen at the time and he had to break it off to a very embarrassed female professor in Berkley.
  • Monty Hall Problem: A topic of one of Charlie's lectures in an episode.
  • Mooching Master: Millie accuses Charlie of being this to Amita in one episode. She raises a couple of fair points about how he uses Amita's time, attention, research, and resources for FBI work. This leads to Amita carefully distancing herself... a little.
  • More Dakka: "Arm in Arms" involved a stolen shipment of guns with a frighteningly high firing rate and muzzle velocity - from which Otto calculated that the guns would overheat and explode if they were used for more than short bursts.
  • Motive Misidentification:
    • The Season 2 episode "Backscatter" has Don and his family directly targeted by the Russian Mob after arresting a couple of phishers connected to them near a bank. Don thinks that It's Personal, but in actual fact, they're targeting him to distract him from investigating the bank, which the mob is planning to rob.
    • In "Sacrifice", it initially appears that a researcher was killed to steal his research. In reality, his killer found his research horrifying, and killed him to stop him from completing it.
    • In "Rampage", a man breaks into the FBI office and starts shooting everything up, but only a suspected pedophile the team was interrogating right before the attack is killed. The FBI initially assumes that the attacker was getting revenge on the pedophile for molesting somebody he knew, especially when they find out the attacker has a daughter in the age range that the pedophile liked to prey on. Then it turns out that Colby was responsible for the death because the bullet he shot through the attacker's shoulder to stop his rampage accidentally went through the interrogation room window and landed in the pedophile's head. Furthermore, the attack itself was a distraction to allow an inside man to smuggle out some confidential data about the witnesses to an arms dealer's current trail during the emergency evacuation so a contract killer can kill and/or threaten the witnesses into silence to get the arms dealer acquitted; the attacker was also an unwilling accomplice, as the contract killer coerced him by threatening to kill his family if he didn't do the attack.
    • "Pandora's Box" involves an intentional plane crash, killing five people. The FBI at first thinks it's due to the prototype scramjet being transported on it, when the real purpose was to hide a virus on the flight data recorder, get the FAA to hook it up to their mainframe, and insert code that would allow the perpetrator to conceal planes from their radar - perfect for drug smuggling.
    • "Blackout" starts with multiple power substations being vandalized all over the city. Theories are thrown around from causing a cascading failure of the grid to union dissent, before it's revealed that the aim was to drain the fuel supply for a prison's backup generators, so that they'd call in an emergency delivery of fuel. This would allow the bad guys to use the tanker as a Trojan Horse to infiltrate the prison so they can assassinate an inmate who's planning on giving the FBI information about their drug operations in exchange for a lighter sentence.
  • Mr. Fanservice: Charlie and Colby. The former appeals to fans of cuter Pretty Boys and the latter to fans of Hunks. The producers are clearly aware of Charlie's attractiveness, exploit it and often makes him emote and Colby has his own fair share of angst, particularly when it comes to the army. Colby also has a thing for getting into the water, and let's not forget the Ho Yay.
  • Multigenerational Household: Alan and Charlie share the same house. Though part of the show, Charlie is the owner.
  • "Killer Chat"; the case is about a Knight Templar serial killer who targets child molesters and finds victims by posing as a teenage girl online, leads them to an empty house, then tortures them to get their recorded confessions. They then murder the molesters.
  • Nazi Gold: In "Provenance", a Pissaro painting lent to a small art museum is stolen. An old Jewish woman and Holocaust survivor named Erika Hellman, who was born in Berlin, claims that it had belonged to her family before they were all sent to the Nazi death camps, and she has been in a court case with the current owner of the painting (who inherited from his Army veteran father after he bought it when World War Two was over) trying to win ownership of it when the episode starts. Both her grandson, Joel, and the current owner become suspects, the former because he's fiercely protective of his grandmother, and the latter because he had a massive insurance payout on the painting. However, in the end, it's revealed the museum curator stole it because he found out that the painting is a fake, much to everybody else’s surprise. The original is found to be sitting in a police vault in Budapest, because Erika's father had commissioned an art forger to recreate the painting and gave him the original for safekeeping so the Nazis would be stealing a fake instead of a priceless painting, and when the Hungarian police arrested the forger in 1946 they had assumed that the painting was one of the fakes they were confiscating as evidence. The episode ends with the Hungarian police sending the real painting to the FBI and Don giving it to Erika and Joel, allowing them to have one piece of their pre-World War II family heritage back.
  • Needle in a Stack of Needles: The case in "Graphic" involved a very rare comic book being hidden amongst forgeries and all being sold off at an auction.
  • Never Suicide:
    • One case is set off by an apparent suicide of an engineering student, which Charlie is convinced was actually a murder because he discovered a big, expensive secret about a skyscraper's faulty construction. While the student did discover the secret flaw, his death was a legitimate suicide because he was already suffering from depression and thought nobody would listen to him any other way.
      • This episode was Very Loosely Based on a True Story. In 1978, an engineering student discovered a very serious flaw in the Citigroup Centre building in New York, that could cause it to collapse in winds over 70 mph. In the real world, he told the architect, who very quickly realized that he was right, and the architect, builder, and owners of the building undertook immediate action to correct the problem. They also informed the city of the problem, and made evacuation plans for the area surrounding the building (though they still kept it a secret from the public) and started watching the weather very carefully until the problem was fixed.
    • Played straight in "Guns and Roses" and "Democracy".
  • New Meat:
    • Colby Granger in season 2 and Nikki Bettancourt in season 5. Colby figures it out pretty quickly (his issue is implied to be more that he's still shaking off the military mindset), but Nikki is in hot water with Don on and off for most of her first season on the show. She does eventually come around, largely because of her guilt over Don's stabbing, and the worst thing she does in Season 6 is throwing herself back into full duty too quickly after a serious car accident.
    • Supposedly, David Sinclair started off as this as well, though in his case, we only know it happened because it's alluded to later. Ironically, his stated issue was the opposite of Nikki and Colby's; he was too cautious and reluctant to take any initiative at all.
  • Nice Jewish Boy: Charlie, though non-observant.
  • Non-Action Guy: Charlie.
  • Noodle Incident: The incident that got Charlie's learner's permit revoked. The only thing we know is that it has something to do with radar guns, which Charlie strenuously insists are unreliable.
  • Not So Different: Despite their different paths in life, Don and Charlie get occasional moments that show they're more alike than they initially appear.
    • In the Pilot, Alan mentions that one of the things they have in common is that they are very thorough.
    • In "Counterfeit Reality", one of Don's ex-girlfriends comments that Charlie's "one part exuberance, two parts obsession" approach to their problem is reminiscent of Don.
    • At the end of "Backscatter", David tells Alan that before he met Don and Charlie, he's never known two brothers who were so different and so very much alike. Alan's response is "Tell me about it."
    • In "The Janus List", Don gest a "Eureka!" Moment of the that the show usually gives to Charlie, and he works through it pretty much the same way Charlie does (only with less math). Charlie even lampshades it.
    Charlie: Is that the face I make when I...?
  • Not-So-Harmless Villain: The second episode has a pair of polite bank robbers. They walk in , request the money, say thank you, and walk out. They are even polite enough to hold doors open for people. Really harmless robbers with a cutesy nickname, or so people think until Charlie predicted their target and Don and a team tries to arrest them. That is when they demonstrated that not having needed to call backup is not the same as not having backup, and not having needed to use violence is not the same as being unwilling to use violence. Turns out they are ex-special forces working to a deeper plan and perfectly happy to use assault rifles, car bombs, and expertly knife a janitor that gets in the way- just hadn't needed to before.
  • Obstructive Bureaucrat: Subverted by Floyd Thompson of Department 44. For all of his odd comments about government dealings, if the team directly asks him for certain information, he delivers it.
  • Oh, Crap!: At the end of "Thirteen", a serial killer the team has just arrested is genuinely confused when the FBI talks about him having killed his accomplice, as he had thought the FBI did it. All at once, the agents realize what this means (that a third party not affiliated with either side was the one that did it), but they're unable to react fast enough to prevent the serial killer from meeting the same fate as his accomplice.
  • Ominously Open Door: Trope Namer. It happens enough to get a a lampshade hung.
    David: Just once, I wish it was a surprise party behind one of these ominously open doors.
  • Omnidisciplinary Mathematician: While far less egregious than other cases, Charlie is an expert at far more fields of math than is realistic, even for a genius like him.
    • Amita too, occasionally.
  • On Three: Delivered by David to Colby, via a Multitasked Conversation, when a gunman has them dead to rights.
    David: Give us one good reason why you're doing this. Okay? Give us two reasons. (Beat) Three!
    (David and Colby spin around and start firing.)
  • Only Bad Guys Call Their Lawyers: Played With. While some of the bad guys do have lawyers, innocent people do occasionally bring a lawyer along when they're being interviewed by the agents.
    • For an example of an aversion, in "Harvest", a patient was discovered with an illegal kidney that he got from a Back-Alley Doctor. The patient's actual doctor immediately contacted his hospital's legal department since he knew law enforcement was going to notice the black-market organ. At the time, the doctor didn't know a girl was accidentally killed in order to get the kidney, but he knew that the incident was going to be investigated and that he would be questioned as part of it, so the legal department paired him up with a lawyer for when Megan went to interview him and collect his patient's medical information as evidence. His having sought legal counsel is never treated as a sign of guilt.
    • It's played straight in "Waste Not"; not only was the lawyer employed by a shady construction company he was a willing accomplice in the crimes the construction company comitted.
    • Another aversion shows up in "Dark Matter". Two teenagers go on a shooting rampage at their high school and when the FBI finds out there was a third shooter, all the members of the school’s video game club become suspects because the two shooters were avid members of the club and were the closest to them out of anybody at the school. Their parents respond by hiring lawyers to help defend their innocence. While the FBI agents react with slight annoyance at this because it impedes their investigation, it's never treated as a cause for increased suspicion. At the end it turns out that the third shooter wasn't involved with the video game club at all; she was a school newspaper club friend of the other two shooters who was raped at a party and masterminded the school shooting to get revenge on the people involved.
  • Open Mouth, Insert Foot: When Don first goes to the department shrink, he is originally dismissive and criticizes the shrink for working out of a textbook with no idea what the FBI is like. He changes his tune when the shrink reveals his own past in undercover narcotics, and doesn't appreciate Don not respecting his past job and expecting him to respect his.
  • Oral Fixation: Don is usually seen chewing gum when he is keyed up during climatic scenes, mostly waiting for the suspect.
  • Organ Theft: In "Harvest", four Indian girls come to the United States, each intending to sell a kidney willingly on the black market to get money for their poverty-stricken families. However, the first girl accidentally dies from a surgical error, and one of the other girls ran and hid inside another part of the hotel basement during the chaos caused by the mistake and was taken into FBI protective custody as a crucial witness when Don and David investigated the disturbance in the hotel and found her. The Back-Alley Doctor running the organ ring subsequently decides to kill the two girls he has left in order to harvest all their organs for the money and to get rid of any potential witnesses. One of the girls ends up dead, but fortunately, the FBI interrupts just before the procedure on the second girl begins (coincidentally, the girl in question was the sister of the girl who was in FBI protective custody), and she is rescued unharmed.
  • Pædo Hunt: "Killer Chat" involves a Serial Killer that lures in, tortures, and murders child molesters.
  • Papa Wolf: Do not try to hurt any of Don's team. And DO NOT try to hurt Charlie.
  • Paranormal Episode: The series had an episode with a psychic helping the FBI, much to Charlie's annoyance, who got rather jealous of the psychic's performance.
  • Parental Abandonment: Not quite, but Amita's parents are always too busy to see her.
  • Parental Incest:
    • "Nine Wives" deals with an Expy'' of the FLDS, a girl finds out that she is the product of Parental Incest- her father married his own daughter, who was apparently so brainwashed that this didn't register as wrong or problematic to her. The girl, who has largely broken out of the cult brainwashing, was not happy about this.
    • "In Plain Sight" features a child pornographer who's been molesting his own daughter; when the mother found out and tried to get the kid away from him, he claimed she was the abusive one and that she had kidnapped the child in an attempt to keep abusing her. Fortunately for everyone except him, the perpetrator was also a Cop Killer, so the FBI had dug into his background and already found evidence of his abuse.
    • The Knight Templar Serial Killer in "Killer Chat" started tracking down and murdering child molesters because she found out that her husband molested their daughter. In fact, he was her first victim.
  • Parental Marriage Veto: Subverted. Amita and Charlie are both very worried that Amita's parents won't approve of Charlie because he's not Indian, but when they finally actually meet Charlie, they are immediately won over.
  • Pay Evil unto Evil: The Theme Serial Killer of "Thirteen" is sniped while in FBI custody by a soldier who was the boyfriend of his very first victim.
  • Perp Sweating: Happens a lot.
  • The Philosopher: Larry, who stayed at a Buddhist monastery for quite a long time and often nudges Charlie in matters of philosophy. Somewhat of a Justified Trope—he studies quantum physics.
  • Phlebotinum Analogy: Charlie often uses these so he can explain his mathematical analyses to those around him.
    Megan: I'm so hoping you have one of those cute little analogies for this.
    Charlie: As a matter of fact, I do.
  • Picky Eater: Larry spends a couple years eating only white food as an experiment.
  • Playing the Victim Card: The main villain of "The Running Man", while faking it the whole time. He claims that his mediocre origins kept him from getting into prestigious colleges in favor of the applicants with hard-luck stories, so he re-enters universities under different names and personas and always with hard-luck origins to sympathize his way in and to get the false celebrity of being a person who beat impossible odds for a better life, vanishing after a year and stealing expensive equipment to finance his schemes. David isn't particularly convinced when the suspect keeps bragging about his rough origins (since he knows from experience that having a rough childhood is something you want to put your distance from when you manage to escape for a better life) and isn't particularly sympathetic when they finally catch him.
  • Please Shoot the Messenger: The episode "Checkmate" revolves around a gang leader in prison who gets hit targets to his gang encoded in chess lessons to a young kid. Then a lesson comes in which, once decoded, tells the gang to kill that kid.
  • Poor Communication Kills: Present in David's bad neighborhood backstory: he was so convinced that his Hot-Blooded friend Ben Ellis was the one that started a fight that got Earl Day, the third member of their ¡Three Amigos!, shot that he never visited Ben in prison, which means he never learned that the normally calm Earl had confronted a guy who was messing with his girlfriend, and the guy responded by shooting him, but Ben took a plea bargain because he knew no one would believe him. David only learns it when his and Ben's paths cross in "Contender", and they eventually make peace.
  • Pregnant Hostage: "Backscatter".
  • The Professor: Larry and Charlie. Especially Charlie, who is incredibly smart and was once a Teen Genius.
  • The Profiler: Megan's specialty.
  • Public Secret Message: In "Counterfeit Reality", an artist is kidnapped by a gang of forgers to replicate the art on dollar bills for them, but secretly puts imperfections in the counterfeit bills that, when viewed a certain way, provides the FBI with her location, just like how she encodes messages to her husband in her art.
  • Pyrrhic Villainy: In the episode "Democracy", the FBI ends up facing a hedge fund investor who rigged an election and then arranged for all but one of the witnesses to be murdered and has someone else take the fall so he walks free, but because Charlie published the math used in the case, election officials would know what to look for and stop any other rigged elections.
  • Quirky Curls: Charlie is a male example.
  • Rape Is a Special Kind of Evil: The darkest episodes of the series are ones that resolve around Serial Killers and rape. It tells you something when in the episode "Dark Matter" the perpetrator who orchestrated a school-shooting is portrayed somewhat sympathetically: all the students deliberately targeted, including her best friend, were complicit in a plot to have her raped after doing a school article on steroid abuse by the school teams. The sole surviving conspiracist is treated as a Jerkass about to get a taste of his own medicine.
  • "Rashomon"-Style: Inverted in an episode. While reviewing the witness accounts of the crime that led to the death of an actor's brother, they realize that the statements are too consistent: they're almost word-for-word identical, when some level of difference would be normal and expected. This leads the agents to believe that the witnesses may have been telling a fabricated story rather than the truth.
  • Real Time: The third season episode "One Hour", in which, while Don talks with his therapist (who has made him turn off his cell phone), the rest of the team has just one hour to crack a case.
  • Reality Ensues: In the pilot episode, no less: Charlie uses his mathematical skills to determine the general area where a serial killer lives based on the locations of his murders, but the FBI fails to find a single viable suspect in the target area. When the FBI finally catches the guy, it turns out that he used to live in the target area, but had moved away prior to the beginning of the episode. No matter how good your math is, there will always be some variables that you can't account for.
  • Reasonable Authority Figure: Don is a textbook example. He's not afraid to give his team members a talking-to when he feels they deserve it, but he by and large treats them as equals and listens to what they have to say, and he even lets Colby back on the team after finding out he was a triple agent. In fact, if he starts shutting his team down or refusing to listen, it's a pretty clear sign that he's in a bad place mentally.
    • The series also shows Charlie to be this as a teacher.
  • Redemption Equals Death: Dwayne Carter, when he shoots Mason Lancer just before he injects Colby with a lethal chemical and gets shot himself shortly after, or at least as close as he ever gets to redemption.
  • Red Shirt: Averted. In one episode, a squad infiltrates a hidden marijuana farm, with several no-named agents. After having specifically stated that those kinds of farms are booby-trapped, it results in an anticlimax where several are disarmed, and nobody gets hurt.
  • Remember the New Guy?: Colby and Megan are introduced in Season 2 with little fanfare or even proper character introductions. They're simply dropped into the team like it's no big deal. Justified, as the FBI is a large bureaucratic organization and these sorts of personnel changes are probably so commonplace as to really not be that big a deal.
  • Remember When You Blew Up a Sun?: Colby Granger from Season 4-6 gets several comments referring to the fact that he was a triple agent.
  • Rewind, Replay, Repeat: Don begins the episode "Trust Metric" watching Colby's confession over and over, because something about it doesn't feel right to him but he can't quite figure out what.
    • In a later episode, he does something similar, watching a suspect's prison psych interviews repeatedly in an attempt to find an angle. It ends up paying off hugely, as he uses the information he gleans to manipulate one of the supsect's disciples into giving up the location of their hideout.
  • Rich Kid Turned Social Activist: Zig-zagged in the episode "Tabu". An heiress joined up with an underground anti-capitalist organization, but Megan deduces that she's just using the group to lash out at her billionaire father and doesn't really care about the underlying cause.
  • Right Behind Me: One episode has Colby quipping that they should get the "whiz-kid" in to take a look at a case, right as Charlie enters the scene. Charlie chooses to take it as a compliment.
  • Right for the Wrong Reasons: In "Rampage", the FBI initially assumes that the guy who attacked the FBI office did so to protect his young daughter from a suspected pedophile the team was interrogating at the time, since he was the only fatality. It turns out that the attacker's actions were motivated by a desire to protect his daughter... because a contract killer threatened to kill her, along with her mother, if the man refused to do the shooting rampage.
  • Ripped from the Headlines
    • "Sniper Zero" (S01, E09) seemed to be all about the Beltway Sniper Attacks.
    • In "Calculated Risk" (S02, E04), it sounded like they were reading directly from Enron's wikipedia page.
  • Running Gag
    • Alan walking in on Charlie and Larry doing some experiments in their house, from building a model complex out of cereal boxes, measuring how ice melts with the house's thermostat, or messing with the shower.
    • A popular one in the later seasons is that whenever the FBI field agents go to a potential suspect, and the suspects run, the agents tend to treat it more as an annoyance than an actual worry that the suspect might get away.
    • There's also one that surfaces occasionally in Charlie's tendency to mistreat whatever random food happens to be lying around to demonstrate a math concept.
  • Russian Roulette: Used as a way to make money from very desperate gamblers and really sick viewers. The organizers even gave the players nicknames and everything; unfortunately for them, it was rigged.
  • Screw the Rules, I'm Doing What's Right!:
    • The finale of season 4: one of Charlie's coworkers is arrested by the FBI because he was sending his biotech research overseas to Pakistan, which the bureau is concerned about even though the research is focused on crop development and is unlikely to be weaponized. At the end of the episode, Charlie sends the rest of his colleague's crop research to Pakistan, then turns himself in to federal custody, and although the charges are dropped, Charlie's security clearance is revoked.
    • In an early season 5 episode, Don brings Charlie in on a case even though his clearance was recently revoked, due to the intensity of the perpetrators.
  • Self-Fulfilling Prophecy: In one episode, a psychic predicts the killers' next move and goes there with his camera. The killers are there, along with their big truck. He doesn't get better, either.
  • Sexy Discretion Shot:
    • Implied at the end of "Checkmate". Don and Robin are leaving a hotel after Robin was put under witness protection, and reigniting their Old Flame after their previous breakup. Don comments that the room is still paid for by the FBI and they never did have their candlelit dinner, then he grabs the room keys back off the front desk and the two hurry back upstairs. The grin that the receptionists share say it all.
  • Shipper on Deck: Nikki seems to be this with David and Colby. She's made several comments about the two of them in a relationship.
  • Shorter Means Smarter: Charlie.
  • Shout-Out:
  • Sibling Team: Don and Charlie.
  • Sibling Yin-Yang: Don is more "jock-like" and Charlie is more "geek-like".
  • Single Serving Friend: Billy Cooper, who Don worked with in Fugitive Recovery before the start of the series, only appears in the first season finale, "Manhunt".
  • Sitcom Arch-Nemesis: Marshall Pennfield, who is Charlie's old rival from Princeton. Near the start of the season two episode: "Convergence", he performs a lecture in which he finds a flaw in the Eppes Convergence, the mathematical theorem that made Charlie famous. Charlie will readily admit that Pennfield is brilliant; he just doesn't like him because he's an insufferable asshole. In the end, Pennfield helps Charlie figure out the case of the week, and when Charlie does find a way around Pennfield's problem, he calls it the Pennfield variation.
  • Smart People Play Chess: It isn't enough that Charlie Eppes could multiply four-digit numbers in his head when he was three, graduated from high school and entered Princeton at 13, completed his bachelors degree in three years and is a multiple PhD. No, just so we'll know he's really smart, he regularly beats his father and his former academic adviser (both portrayed as above-average intelligence) at chess, too.
    • Justified. Chess is a proponent of game theory with a zero-sum outcome in which all information is available and possible moves are restricted based on previous moves. Hence it really comes down to a calculation of possible outcomes weighed against a target outcome. The reason why mathematicians tend to be good at chess is because chess is based in a very specific form of game theory. Why does Charlie always play and always win? Because he's Good with Numbers, chess is about as close as game theory gets to pure mathematics, and he's a mathematician. Although, considering that most of his math deals with statistical models and application it would probably be more appropriate for him to be playing black jack.
      • Which Dr Fleinhart did to the point of being banned from casinos, making him doubly smart!
    • It's been shown that the only way to have a reasonable chance at beating Charlie at chess is for two people to play against him at once while also having a distraction.
    • Mostly averted with Millie, who, after challenging Alan to a game, admits to Charlie that she's never actually learned how to play and has to try and learn the game in the day and a half before she's set to play him. She does beat him, but her approach to the game is less pure strategy and more people-reading skills. (She's very good at poker.)
  • Smurfette Principle: At least early on in the series. The cast is mostly male with one female FBI agent at a time (Terry first, then Megan takes her place) and Amita. This is then subverted in Season 3 when they add Liz, but Amita is still the only female character who lasted the whole series.
  • Sole Survivor: In "Provenance", Erika Hellman was the only member of her family in Berlin who survived the Holocaust, and was six years old when it happened.
    Erika: You have no idea what it's like to be the only survivor of your family and to have no idea why.
  • Somebody Set Up Us the Bomb: The episode "Cover Me" has a flashbang grenade delivered in a duffel bag.
  • Spanner in the Works:
    • The killer acts as a villainous version of this for Charlie in the pilot episode: He develops an equation that is meant to identify the killer's home based on the locations of his previous offenses and it would have done exactly that if not for the fact that the killer happened to move out of the identified area a few weeks earlier.
    • In "Bettor or Worse", the plan for a jewelry store manager with massive gambling debts and a bookie in a lot of trouble to pay off their associates by arranging for the manager's family to be kidnapped and for the bookie's sister to rob the store is derailed by the lone security guard shooting the robber.
  • Speak in Unison:
    • When David and Colby are caught in a shootout along with resident Conspiracy Theorist Roy McGill:
      McGill: This is just like Waco!
      David and Colby: Shut up!
    • In "Sneakerhead", David and Liz encounter two of the involved individuals (a foreign consul and a famous rapper) arguing about a pair of $250,000 sneakers that were recently stolen. When Liz reveals that they found one of the sneakers on the foot of a dead perp, the two arguers exchange a horrified look and say together:
      He wore them?! THAT LOWERS THE VALUE!!
  • The Spock: Dr Fleinhart. Charlie doesn't qualify, as he emotes just fine.
  • Spotting the Thread: In "The Running Man", David gets suspicious of a suspect named Ron Allen when he keeps invoking his rough childhood to the point where he's practically bragging about it, something that David knows from personal experience one usually puts their distance from when one gets a better life. This prompts him to do a deep background check on the suspect, and he discovers that the real Ron Allen died in infancy.
  • Standard Cop Backstory: The show has a few.
    • Megan Reeves was wealthy, but her father resented her because she was born a girl when she was his last chance to have the son he wanted, and it's hinted (but never confirmed) that there's more to the story. Whatever did happen, it was bad enough that she left home when she was 16 and didn't speak to him for over a decade.
    • David Sinclair grew up in a poor neighborhood "dodging gangs just to get [his] high school diploma". His father died when he was in his early teens, and one of his best friends was killed in a random act of violence (for which another friend was unfairly blamed).
    • Colby Granger's father died in a single-car wreck when he was fifteen. There's no way to be sure, but Colby has always suspected it might have been a suicide. He also spent several years in the military.
    • Recurring character Ian Edgerton also has a military background; the rest of his backstory is a complete unknown.
    • Notably averted with Don. Charlie's being a prodigy caused a few small issues, but he was always loved and cared for. There's a reason that he's still so close with his family. He does have a few failed relationships, but that's implied to be mostly by choice.
  • Stealth Hi/Bye: The specialty of mysterious government Agent Floyd (minus the "Bye" part), to the annoyance of Amita: "Stop materializing out of thin air!"
    • Cold Sniper Edgerton also has a habit of doing this, but, then again, he is a sniper. He made a surprise appearance at the end of Season 6, then asked why he wasn't invited to Charlie and Amita's wedding that was planned in one day.
  • Stealth Pun: Possibly the name Eppes constitutes one. Amita: "Charlie, wonderful news! You are now father of an...Eppesilon!" (Don't Explain the Joke mode: Famous mathematician Paul Erdős was known for calling children "Epsilons". It's derived from the Greek letter epsilon being standard use for the arbitrarily small quantity in the definition for the continuity of a function).
  • Take a Third Option: In the series's penultimate episode, Charlie and Amita get offers for visiting professorships in Cambridge, in the middle of their wedding preparations, leaving them stuck between either forgoing the professorship, getting married in England with major travel difficulties for their family and friends, or postponing their wedding to even later. In the end, they decide to take the fourth choice: get Larry to marry them tomorrow.
  • The Stoic: Don.
  • The Storyteller: Charlie Eppes teaches math with stories. He would be great to have as one's professor.
    • Larry indicates that he gets amazing class evaluations.
  • The Strategist: Charlie would probably qualify with his ability to mathematically predict the moves of evildoers.
  • Straw Vulcan: Usually averted.
  • Suspiciously Similar Substitute: Twice, and both times it has been the female FBI team member. An interesting example because while Megan shares characteristics with both the character she replaced (Terri) and the character who replaces her (Nikki), Terri and Nikki don't have much in common at all, it's just that Megan has very strong attributes that correspond with both. With Terri and Megan the trope comes into play as they're both The Profiler; with Megan and Nikki it's more about the Action Girl aspect.
  • Sympathetic Murderer: While it doesn't excuse their crimes, a lot of the killers do have sympathetic motives.
    • The one who caused domino-effect killings (he shoots at Gang A, who retaliates against Gang B, who retaliates back, people get caught in the crossfire...repeat until about 150 people are dead) to avenge his young son who was murdered by gangsters. By the time the crew catches up with him, he is very clearly insane.
    • The Knight Templar murderer who targets child molesters in "Killer Chat" turns out to be the wife of a pedophile who had sexually abused the couple's daughter. Despite the brutality of the crimes, it's hard not to sympathize with the killer once the motive is revealed.
    • The killer in "Sacrifice" becomes a lot more sympathetic when we learn his motive: the victim was developing a computer program that would have allocated educational resources based on a mathematical assessment of "potential" (as Don puts it, the government would use it to justifying taking money away from poor communities and making sure only the wealthy got opportunities), and his assistant Scott, who came from a poor neighborhood, knew that such a program would have denied him the opportunities that allowed him to escape for a better life, and that other people like him would be denied any opportunity for a better life if the program were ever implemented. Once he's arrested and explains his motives to Charlie, Scott compares what his boss was doing to the Nazis using the Theory of Eugenics to justify murdering the poor and those that they had deemed "undesirable", as both programs would take somebody's chance of life away due to factors beyond anybody's control. At the end of the episode, Charlie comes to agree with Scott that potential can't be measured mathematically, even though he doesn't condone the murder, and he destroys the victim's work so nobody else can take advantage of it.
    • One shows up in "Velocity". He was a street racer until he caused a fatal accident, whereupon he swore off it for good. But when some of his old racer acquaintances (who often drove past him to mess with him) caused a crash at one of his hangouts and killed a new friend, he ended up beating the one responsible to death. That's the sympathetic part; the part where he kicked a 17-year-old who he thought was responsible for the crash in the head, less so.
    • In "Thirteen", an ex-army sniper performs Vigilante Executions on the serial killers who tortured and murdered his girlfriend, having tailed the police to find them. It doesn't excuse his actions (both serial killers were in custody, so there was no threat to anyone), but it's almost hard not to sympathize with the guy.
    • The plot of the series finale involves two near-misses on this: a battered woman whose boyfriend keeps violating his restraining order, and a teenage boy whose neighbor has been bullying his family. However, the woman is unable to bring herself to do it, and the other attempt is interrupted by the FBI.
  • Talking the Monster to Death: The climax of "7 Men Down" has David, Colby and Nikki bust into the last round of a Russian Roulette tournament, but all the gang members present and betting on the outcome immediately pull their guns on them. When putting their guns away doesn't defuse the situation, David, knowing the game is rigged, makes a bet himself, but also challenges the second player, who is the one who rigged the guns and had never lost a round, to go first. When he refuses, the gangs realise what's going on and also put their guns away.
  • Tangled Family Tree: In "Nine Wives", a family tree diagram found in a cult leader's trailer is so convoluted (due to the massive number of marriages each man has, as well as the prevelance of incest within the cult) that Charlie and Amita initially aren't sure what it is, and only figure it out after Millie mistakes it for a cattle breeding chart (which is close enough to "family tree" for Charlie and Amita to finally realize what it actually is).
  • Teacher/Student Romance:
    • Charlie and Amita. He's only her thesis advisor! Really! Less weird in that since Charlie was a child prodigy, they're about the same age. Also, Charlie doesn't begin dating her until after she finishes her thesis, when he's no longer in a position of authority over her.
    • A much weirder and less acceptable example underlies the plot of the Season 3 premiere.
  • Team Dad: Don.
    • Alan, too. And not just in the sense of actually being Charlie and Don's father—he will at times give everybody useful advice or be a sounding board for problems.
  • Tempting Fate: When David and Colby corner a gun-wielding suspect in a garage that was recently used to make bombs:
    David: Sir, you're in a bomb lab! Now you know better than-
    Suspect: AAAAHHH! (Pulls the trigger)
    Colby: ...apparently not.
  • Theme Serial Killer: A serial killer whose victims had the same names as the 12 apostles and killed them in the way each apostle died.
    • Not only that but the locations of their deaths were consistent with a map of the last significant events of Jesus's life.
  • Therapy Is for the Weak: After the Crystal Hoyle incident, Don is encouraged to go to therapy, and is initially resistant to the idea before he finally gives in.
  • There Should Be a Law: David basically acts like this in "Arm in Arms" toward the legal arms dealer Arvin Lindell, including basically kidnapping him, driving him out to a memorial, and leaving him there.
  • This Looks Like a Job for Aquaman: Alan sometimes offers his insight on a few of Don's cases, usually relating to his old profession as a city planner.
  • Throw the Dog a Bone: In "Jack of All Trades", the FBI are after a conman that has stolen thousands of dollars from multiple companies. Once they find out that the conman, Kevin Oliver, is only 18 and his main motivation is to find his birth mother, after tracking down the mother themselves and using her as bait to draw him out, Don gives Oliver a few moments with her, over the objections of the Inspector Javert working with them.
  • Treacherous Advisor: Some episodes have certain advisors, from arson experts and anti-terrorism experts to ordinary comic book experts, helping the FBI with their case, but who turn out to have orchestrated the case themselves for whatever reason.
    • Subverted in "The O.G.". The guns used to orchestrate several shooting chains between gangs turned out to have all come from a gun buy-back program and all signed off by Lieutenant Gary Walker, who was advising the team up to this point, however as Walker points out, his signature only means they were turned in at his drop-off location, and there were other people involved with the program who would also have had access to the guns.
    • Played with in "Scratch" via a Bait-and-Switch; it's initially thought that the lottery expert working with the team is the inside man, but later it turns out that it's their boss that's the inside man.
  • Unit Confusion: Occurs in-universe in "Thirty-Six Hours". Charlie gives Colby a series of very precise directions to get into the wreck but forgets to specify unit of measurement; he means them in meters but Colby counts them out in yards, causing him to run into a dead end. Charlie figures it out fairly quickly, and it ends up being little more than a minor inconvenience.
  • Video Arcade: In the Pilot, Charlie and Larry meet in an arcade on campus on CalSci, where Larry gives Charlie some advice on the current case, while simultaneously getting a high score on his current game.
  • Villain Has a Point: The victim in "Sacrifice" was killed because he was developing a computer program that would have allocated educational resources based on a mathematical assessment of "potential" (or as Don puts it, it’s a justification to take money away from poor communities and make sure only the wealthy got opportunities). His assistant, Scott, grew up in a poor crime-ridden neighborhood, and knew that such a program would have denied him the opportunities that allowed him to escape for a better life. He also knew that other people like him would be denied any opportunity for a better life if the program were ever implemented. Once he's arrested and explains his motives to Charlie, Scott compares what his boss was doing to the Nazis using the Theory of Eugenics to justify murdering the poor and those that they had deemed "undesirable", as both programs would take somebody's chance of life away due to factors beyond anybody's control. At the end of the episode, Charlie destroys the victim's work so nobody can take advantage of it even though he refuses to condone the murder.
  • Virtual Danger Denial: A Playful Hacker cheerfully pisses off a number of powerful agencies online, legal and illegal, and is in total denial that they could come after him in real life. At least until it gets one of his loved ones killed.
  • Walking the Earth: Larry is always doing this or wanting to.
    • Except when he went into space.
    • Then when he went into the desert.
  • The Watson: AKA the FBI.
  • Wedding Finale: The sixth season (and series) finale had Charlie and Amita's wedding.
  • Well-Intentioned Extremist:
    • The scientist who intentionally infected people with Spanish Flu to prove that the pharmaceutical companies chose the wrong (less virulent) strain to use in the development of vaccines and treatments, because he was convinced that a real epidemic was only a matter of time and so getting it right was literally a matter of life and death.
    • The Homeland Security agent who saw vulnerabilities in counter-terrorism operations that had to be patched, and tried drawing attention to them by using a deadly gas in one of them (watered down to prevent casualties). When that didn't work, he planted a (fake) bomb on his boss to make him feel the fear of soldiers saddled with ineffective strategies and protections.
    • The Knight Templar Serial Killer in "Killer Chat" who targets child molesters so no kid would ever be hurt by one again after her husband molested their daughter.
    • The man who started killing gang members in such a way as to maximize retaliations, with the intent of getting as many gang members as possible killed off, after his son was killed in a gang war.
    • The narcotics cop who was feeding a gang member the locations of rival gangs' stash houses so he could raid them, figuring that fewer drug dealers was better for the community. He crosses the Moral Event Horizon when the gang member decides he's had enough and wants to come forward; he arranges for the gang member to go down in a raid, and then kills the cop who pulled the trigger when he starts to piece together that something wasn't right.
    • The Neighborhood Watch types who got ahold of Don's gun used it to kill a pair of drug dealers who sold to schoolchildren and a serial drunk driver who ran down two people, and to intimidate a vicious neighbor who turned out to be an escaped murderer.
  • Wham Line: From the Season 3 finale, "The Janus List". The entire episode has been about getting a list of double agents, not because they were seeking the list itself, but because its author is setting off bombs in a roundabout way, to make Charlie and Don prove they were worthy to receive the list. They figure out the clues, stop the bombs, and listen to the list...
    Janus List: Colby Granger, FBI, also working for the Chinese.
    • In the following episode, "Trust Metric", Big Bad Lancer gets one when he has Colby on the freighter:
      Lancer: That's a question I need answered, Agent Granger.
      Colby: Oh, it's not "Agent" anymore.
      Lancer: Mike Kirkland says differently.
    • A more personal example in "One Hour", when Don's therapist finally goads him into revealing the extent of his trust issues. It's as much of a Wham to Don himself as anyone, since even he hadn't been consciously aware of how bad his problem was.
      Don: Look, I'm their boss! I don't have to trust them; it's their job to trust me!
  • What Does She See in Him?: At the end of "Toxin", Absent-Minded Professor Larry admits he's starting a relationship with Megan Reeves, and gets a bit huffy when the Eppes men start joking with him about it. Colby, David, and engineering professor Ray Goleski have all discussed the unusualness at some point.
    Charlie: Megan?
    Don: And Larry.
    Alan: Now there's an image.
  • What Happened to the Mouse?:
    • At the beginning of Season 2, a prosecutor named Nadine was set up as a potential love interest for Don. She shows up twice more and then disappears and is never so much as talked about for the rest of the series.
    • The season 5 episode "Animal Rites" teases a possible budding relationship between Larry and another professor named Lorna. Lorna is never seen or mentioned again.
  • Who Would Want to Watch Us?: In the episode "Graphic", after Don and Charlie have returned a rare comic to its artist, said artist begins drawing them and suggests a complete comic series about an FBI agent and his Mathematician brother. Cue Don's line of "Aw, no-one would believe it."
  • Will They or Won't They?: Charlie and Amita.
    • They Do: They got married.
    • And Don and Robin. In the final episode, they get engaged.
  • Working with the Ex: Between fellow FBI agents Terri and Liz, federal prosecutor Robin, and even one-off characters like a counterfeit specialist from the Secret Service, Don runs into a lot of his Old Flames throughout the job.
  • Would Hurt a Child: The FBI deals with child kidnappers, pedophiles and violent offenders throughout many episodes, but one that takes the cake is "Waste Not", where a company responsible for paving school playgrounds also buried barrels of toxic waste underneath them that eventually leaked and, in addition to turning the school into a cancer cluster, caused a sinkhole that trapped several kids, caused chemical rashes, and even killed a teaching assistant.
  • Writer on Board: The eco sub-arc, the season finale about treatment of minorities from "risky" areas of the world.
  • Writers Cannot Do Math: Zigzagged like crazy.
  • You Meddling Kids: Seen at the an of an episode, in which Don, his team, and Charlie investigate spooky activity at a supposedly abandoned airbase. This is more of an inversion, thought, as it is very ambiguous whether the person that said it was a villain at all, and he had helped them solve the case. He is also very wacky, talked in an invisible cell phone and appeared out of thin air. He also called three professors and an FBI agent meddling kids.


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