Dr John Watson has just returned from service in Afghanistan with Bad Dreams, a psychosomatic limp and a bullet wound for his trouble. John's therapist encourages him to keep a blog about his life as a returned vet, but it doesn't seem to help since, as John himself puts it, "nothing happens to [him]". And to top it all off, his army pension isn't enough to keep living in London. All in all, things are kinda crappy for John until he runs into Mike Stamford, an old friend from his days at St Bart's. As it happens, Mike knows of someone who's looking for a flatmate...
As if to prove this, Sherlock Holmes is introduced to John beating a cadaver with a riding crop For Science!, being completely oblivious to the advances of the St Bart's morgue attendant Molly Hooper and texting people the solutions to murder cases. From a glimpse of John and a brief lend of his mobile phone, Sherlock is able to deduce that John is an army doctor home from service with a psychosomatic limp who disapproves of his alcoholic divorcee brother (though he wasn't quite right).
John goes to look at the flat with Sherlock and quite likes it. Sherlock introduces him to the landlady, Mrs Hudson, for whom he did a favour once. After John agrees that the flat would be a good place to live, he is interrupted by the arrival of Inspector Lestrade, who needs Sherlock's assistance with the fourth in a series of identical suicides that have been occurring. Sherlock leaves, before returning to ask John to come along, since he's a qualified doctor who might be able to help. In the taxi, they talk and Sherlock explains his job: he's a consulting detective, one who helps the police with problems when they're out of their depth. He also explains his first deductions of John. John is amazed, naturally, and Sherlock is intrigued by someone who appreciates his deductions.
They go look at the corpse, a woman dressed in pink. When they get there, John finds that the police don't like Sherlock — the first officer they meet, Sgt Donovan, calls Sherlock 'freak' and another officer, Anderson, seems to really dislike him (after Sherlock reveals his affair with Donovan, it's easy to see why). Sherlock and John examine the corpse and find a few anomalies: one, she wrote 'rache' on the floor next to her. While Sherlock recognises this as being an incomplete 'Rachel', the question still remains: why? Two, Sherlock sees that she had a suitcase, but no suitcase was found. Finally, her phone is missing. Sherlock has a brainwave and runs out of the scene, leaving John to walk home. On his way out, Donovan gives him some advice: stay away from Sherlock, whom she calls a psychopath who gets off on crimes and puzzles. She also says that she fully expects Sherlock to eventually get bored of solving crimes and start committing them. John gets back to the main road and phones around him start ringing. He finally answers one in a public phone box and is picked up and taken to an empty warehouse, where a man with an umbrella identifies himself as the closest thing Sherlock has to a friend (an enemy) and offers John money to spy on Sherlock. John declines and is taken back to Baker Street.
John tells a remarkably unfazed Sherlock about the man's offer. Sherlock isn't bothered by the event and asks John to text a message to a certain number. John sees that Sherlock has the woman's case, and texts the message to the number- the victim's phone. The message is designed to freak out the murderer and gives an address. Sherlock and John go to a restaurant near the address and when a cab arrives, they chase it. However, the cab's passenger has a perfect alibi, and they return home only to find a drug bust in progress- Lestrade, thinking that Sherlock was withholding evidence, orchestrated the bust so he could search the flat. They find nothing, but a cabbie arrives for Sherlock, and he's got the victim's phone. Sherlock follows the cabbie outside, where the cabbie tells him that he doesn't actually kill his victims — he talks to them and they kill themselves. Holmes' curiosity gets the better of him, so he gets into the cab.
Sherlock and the cabbie drive to a specially-chosen place, where they play a psychological mind game. The cabbie explains that he has a sponsor, a person who is giving him money for each person he kills, money that will go to his children. In addition, he's dying and thus has nothing to lose. Sherlock milks the killer for information while the killer reels Sherlock in by suggesting his game as the ultimate test of Sherlock's observation and judgement. John follows Sherlock, but the trail ends with two seemingly identical buildings. He picks the wrong building, but at the crucial moment, he shoots the cabbie through a window. Sherlock manages to get the name of his sponsor out of the man — Moriarty.
Outside, Sherlock talks to Lestrade about the cabbie until he realises that John killed him. The man with the umbrella and his assistant arrive, and Sherlock reveals who he is — Mycroft, Sherlock's older brother. They have a brief fight before Sherlock and John leave, and Mycroft decides to step up surveillance on his younger brother.
Tropes present in this work include:
- Actually Pretty Funny: Sherlock jokes about a serial killer while John unsuccessfully tries to keep a straight face.John: [laughs] Stop. [holding back laughter] We can't giggle—it's a crime scene, stop it.
Sherlock: You're the one who shot him, don't mind me.
John: Keep your voice down! [giggles]
- Adaptational Villainy: Jefferson "Jeff" Hope, the cab driver responsible for the murders, uses the same methods as his counterpart in A Study in Scarlet, but most of his sympathetic motivations are removed. In the book, he was an embittered Vigilante Man trying to avenge his wife's death at the hands of fanatical Mormons. In the show, he's a serial killer with a brain aneurysm, who is murdering innocent people for the thrill of outliving others and because Moriarty is giving him enough money to support his children when he's gone. Additionally, the original Hope was captured and confessed, but died in jail shortly thereafter.
- Alone with the Psycho: Played With. Sherlock leaves the flat, ostensibly to "get some air", leaving John to sit about in confusion and continue trying to track down a victim's phone through its GPS. After only a few minutes, John realises that the phone was at Baker Street because the cabbie who was there a few minutes ago had it - and now it's moving again, because Sherlock went out after him, putting Sherlock Alone With the Psycho. Played with in that Sherlock knows full well he's Alone With the Psycho, and actively put himself in that position.
- Answer Cut: When John asks his friend who the first one was that morning to ask about a flatmate, the scene cuts to Sherlock.
- Are You Pondering What I'm Pondering?: There is a hilarious misunderstanding when John comes to see the flat and thinks out loud that it needs cleaning while Sherlock at the same time notes that this was him moving in.John: Well, this could be very nice. Very nice indeed.
Sherlock: Yes, I think so, my thoughts precisely.
Sherlock: So I went straight ahead and moved in.
John: Soon as we get this rubbish cleaned up.
- Batman Gambit: Jeff Hope pulls one in the final moments of the show. Sherlock already figured out he has no reason to accede his captor's demand to play the deadly game because he has nothing holding him to, the killer's weapon being a prop lighter. As he leaves, Hope asks if Sherlock had figured out which bottle was really poisoned and by that simple question, Sherlock gets baited into playing the game simply by his own desire to prove himself.
- Beneath Notice: Cabbies. Everyone trusts them without knowing them. They hunt in crowds because all everyone thinks about is the back of a head.
- Berate and Switch: When Sherlock gets John hooked on becoming his partner.Sherlock: Seen a lot of injuries, then. Violent deaths.
John: Well, yes.
Sherlock: Bit of trouble too, I bet?
John: Of course. Yes. Enough for a lifetime, far too much.
Sherlock: Want to see some more?
John: Oh, God, yes.
- Big Brother Is Watching: The most direct example of the series; Mycroft uses CCTV cameras on the street to watch John. Also, he is literally a big brother to Sherlock and tries to bribe John into spying on him.
- Big "SHUT UP!": Sherlock does this to everyone in 221B while trying to think about the matter at hand.
- Bland-Name Product: MePhone.org.uk
- Blood Knight: Mycroft suggests that John is one, evidenced by how calm and capable he is in dangerous situations, compared to his shakes and his limp in everyday life. As he so astutely notes about the real reason John is seeing a therapist;
- Butt-Monkey: Anderson.Sherlock: Anderson, don't talk out loud. You lower the IQ of the entire street.
- Catapult Nightmare: The first scene is Watson waking up catapulting from a dream of Afghanistan.
- Character Blog: You can look up Sherlock's website and Watson's blog but Watson's was blank for a while.
- Chekhov's Gun: John has a gun in a drawer shows in the first minute. He takes it later.
- Comically Missing the Point: The entire exchange between Sherlock and Molly revolving around coffee and Sherlock noticing her lipstick (not because she looks nice, but because the lack of it "makes [her] mouth look smaller").
- Confess to a Lesser Crime: In a variation, Holmes was able to get Angelo, the restaurant owner, out of a triple murder charge by proving he was in a completely different part of town, house-breaking, at the time of the murders.Angelo: But for this man, I'd have gone to prison.
Sherlock: You did go to prison.
- Couldn't Find a Pen: A woman clawed a vital clue into the floorboards.
- Cut Apart: After realising Sherlock's gone off with the murderer, John tracks them down to a college campus. After frantically searching the building next to where their taxi is parked, he gets to a room with big windows only to see Sherlock and the murderer in the building next door. He makes the most of it by shooting the killer through the window.
- Dead Man Walking: Sherlock deduces that Jeff Hope is one, and even describes him as such. It's then confirmed by the man himself, revealing he's suffering from an aneurysm and that any breath he takes could well be his last.
- The Dog Was the Mastermind: The serial killer turns out to be a cabbie, seen earlier when Holmes and Watson chased down his cab because they thought the passenger might be the killer
- Double Take: John gets in a blatant one after Sherlock tells him that girlfriends aren't really "his area". Is he gay?
- Dying Clue: One victim scratches the word 'rache' into the floorboards with her fingernails. Sherlock correctly deducts this to be a clue to her phone password.
- Establishing Character Moment:
- Sherlock has a show-stopping one when he first meets John. It is, naturally, a startlingly accurate analysis of John and his background after having known the man for all of two minutes.John: Is that it?
Sherlock: Is that what?
John: We've only just met, and we're gonna go look at a flat?
John: We don't know a thing about each other. I don't know where we're meeting, I don't even know your name.
Sherlock: I know you're an army doctor and you've been invalided home from Afghanistan; I know you've got a brother who's worried about you but you won't go to him for help because you don't approve of him; possibly because he's an alcoholic — more likely because he recently walked out on his wife, and I know that your therapist thinks your limp's psychosomatic; quite correctly, I'm afraid. That's enough to be going on with, don't you think?
- John's ECM goes like this:Sherlock: You're a doctor. An Army doctor.
Sherlock: Any good?
John: Very good.
Sherlock: Seen a lot of injuries, then. Violent deaths.
John: Well, yes.
Sherlock: Bit of trouble too, I bet?
John: Of course, yes. Enough for a lifetime, far too much.
Sherlock: Want to see some more?
John: Oh God, yes.
- Sherlock has a show-stopping one when he first meets John. It is, naturally, a startlingly accurate analysis of John and his background after having known the man for all of two minutes.
- Even Evil Has Loved Ones: Jeff Hope has his son and daughter, who he wants to provide more money for after his death.
- Explain, Explain... Oh, Crap!:
- Sherlock has a Eureka Moment when talking about the female victim's hair.Sherlock: She colour-coordinates her lipstick and shoes. She'd never have left any hotel with her hair still looking... Oh... Oh! Serial killers, always hard. You have to wait for them to make a mistake.
- At the end, when Sherlock agrees to help Lestrade figure out who killed Jeff Hope.Sherlock: The bullet they just dug out of the wall is from a handgun. A kill shot over that distance from that kind of a weapon? That's a crack shot you're looking for, but not just a marksman. A fighter. His hands couldn't haven't shaken at all, so clearly he's acclimatized to violence. He didn't fire till I was in immediate danger, though, so strong moral principle. You're looking for a man probably with a history of military service, nerves of steel...
[Sherlock looks over at John, and realizes that he was the shooter]
Sherlock: Actually, you know what? Ignore me.
Sherlock: Ignore everything I just said. It's just the...the shock talking.
- Sherlock has a Eureka Moment when talking about the female victim's hair.
- Extremely Short Timespan: The time in the episode from the discovery of Jennifer Wilson's body to the encounter between Sherlock and the serial killer cabbie, which leads to the resolution of a Study in Pink, occurs all in one night.
- First-Episode Spoiler: Mark Gatiss's character is hinted for the duration of the first episode to be Moriarty, but he's actually Mycroft Holmes.
- Five-Second Foreshadowing: When Sherlock mentions Watson's brother, Watson glances over at him with a confused "Hmmm?", clearly having no idea what Sherlock is talking about. In the next scene, Watson informs Sherlock that "Harry" is his sister Harriet.
- Fixing the Game: This may more properly belong under YMMV, but nevertheless it's a distinct possibility. Think about it. The odds of four consecutive victims each picking the poison instead of the harmless pill is in the single digits.note The cabbie couldn't afford to let any victims live, because then they'd have gone to the police, the game would have been up, and he'd have been behind bars with no more money from Moriarty going to his kids. Both bottles contained poison pills. We only have the cabbie's word that he swallowed the pills in the other bottle, when he could just have easily have told the victims "let's wait a moment to see if you chose correctly." By the time the symptoms of the poison hit, it would have been too late for the victims to seek help or try and vomit up the pills. The victims had no chance and he was sadistically offering them false hope. Sherlock knew this, which was why he deliberately drew things out and made such a show out of getting ready to take the pills before Watson shot the cabbie.
- When Sherlock and John go to the crime scene near the beginning, they hail a cab and hop in without so much as glance at the driver. It turns out, the killer trapped his victims by exploiting similar behavior in them.
- During the opening scene, John's cane is placed across the room from him, where he couldn't readily access it if he needed to. This is an early sign that his leg pain is psychosomatic and that he's prone to forgetting about it.
- Sherlock tells John that the frailty of genius is that it requires an audience. Jeff Hope uses this to bait Sherlock into playing his game, even after he has no reason to.
- Freeze-Frame Bonus: If you pause at just the right time when Sherlock and John catch up with the cab, you can spot Jeff Hope sitting in the driver's seat.
- Gender-Blender Name: Harry turns out to be Harriet, John's lesbian(?) sister.
- Getting Crap Past the Radar: Holmes deduces that Donovan spent the night with Anderson. "And I assume she scrubbed your floor, going by the state of her knees."
- Good All Along: Mycroft. In this episode, he gives the impression of being an Affably Evil criminal mastermind with a bone to pick with Holmes. Savvy viewers would be forgiven if they thought he was meant to be Professor Moriarty until the end when it's finally revealed to Watson and the audience that he's Sherlock's brother. When he said he was "concerned" with Sherlock, he was being genuine.
- He Is Not My Boyfriend: When the pair have a stakeout at a restaurant while waiting for the murderer to appear, the waiter refers to John as Sherlock's 'date', which he immediately denies. The waiter pays no attention to this and afterwards brings a candle for the table.
- Hypocritical Humor:
- John's first meeting with Mycroft.Mycroft: [after showing Watson he can control all the cameras in London and taking him to a secluded location via limo] He [Sherlock] does so love to be dramatic.
John Watson: Well, thank God you're above all that.
- Sherlock considers playing the violin while he's thinking and occasionally bouts of muteness to be his worst habits. He conveniently omits storing bits of dead people in the fridge and firing a handgun into the wall when he's bored.
- Later Sherlock convinces John to join him on a mission so he can talk to him about his revelations. The next scene, he remarks of the serial killer "that's the frailty of genius, it always needs an audience"; John is quick to agree.
- John's first meeting with Mycroft.
- Jack Bauer Interrogation Technique: Holmes uses this on the taxi driver to get Moriarty's name. Even if you're dying, you can still feel pain.
- Jumped at the Call: John, the first time Sherlock invites him to come along on a case:Sherlock: You've seen a lot of trouble, too, I expect?
John: Of course, yeah. Enough for a lifetime. Far too much.
Sherlock: [Beat] Wanna see some more?
John: Oh, God, yes.
- Love Makes You Evil: As Sherlock puts it when working out the motive of a serial killer, "Bitterness is a paralytic. Love is a much more vicious motivator".
- Kidnapped by an Ally: The man who's stalking John through CCTV and has him kidnapped and taken to a warehouse is actually Mycroft, rather than Moriarty.
- The Man Behind the Man: We learn that the cabby serial killer had a sponsor — Moriarty.
- Manipulative Bastard: The serial killer. He first talks Sherlock into his Evil Plan without even using his gun by manipulating Sherlock's arrogance and curiosity. Then, once Sherlock reveals that the gun is a fake in any case and he has no need to take a pill at all, he gets him to take it anyway to prove that he's really the smartest. He's only stopped by a well-placed shot from John.
- Interestingly, the serial killer in the pilot version of the first story was not this way at all: the cabbie simply drugs Sherlock in public (with everyone around assuming thanks to his acting that he's simply drunk), drags him back to his home, and presents him with the pill game when Sherlock is still too drugged to really fight him off. He even threatens to simply force the pill down his throat if Sherlock refuses. The cabbie only tries manipulating him after the police have arrived outside, thanks to John noticing something was off.
- Mistaken for Gay: The dinner stakeout with Sherlock and Watson starts a running gag that continues into the second series.
- Mundane Solution: Turns out Lestrade's advice of "don't commit suicide" works pretty well, though it's harder to follow when what appears to be a gun is aimed at your head.
- Mythology Gag: Much of the story makes reference to the original source story A Study in Scarlet.
Sherlock: No, she was writing an angry note in German. Of course she was writing Rachel!
- A character who is a Red Herring for being the murderer is an American visiting London for the first time. In A Study in Scarlet, the murderer was an American visiting London for the first time. In both, the killer is a cabbie.
- In the original story the police assumed that the person writing Rache was trying to write the name "Rachel", and Holmes pooh-poohed this by advising them that "Rache" is German for "revenge". Here, the interpretation is reversed in that the victim actually was trying to write Rachel out.
- John finds Sherlock lying down on the sofa moving his arm in a way that made it look (from the audience's POV) as if he had just treated himself to a ringer of cocaine.
- It's a three-patch problem = It's a three-pipe problem.
- The fact that Sherlock is on the nicotine patch instead of smoking his pipe: There's hardly anywhere in London where he can legally smoke in public any more.
- Sherlock's analysis of Watson's phone is almost identical to a passage in the original story where Sherlock shows off his deductive process on Watson's watch. However, one important detail is changed: Sherlock actually gets something wrong. In both versions, he guesses that Harry is Watson's brother. In the book he's correct. In the show, Harry is short for Harriet, who is Watson's sister.
- In "The Problem of Thor Bridge", Watson mentions a case involving a man named James Phillmore who disappeared after going back for his umbrella. One of the victims in "A Study in Pink" is a man named James Phillmore who disappears after going back for his umbrella.
- In the story, Hope is baited up to Holmes' room, where he has the cuffs slapped on him. He tries to escape by jumping out a window, only for Holmes, Watson, Gregson, and Lestrade to catch him. In this, he comes up to the room himself, leading to Holmes figuring it out and going downstairs and having a chat with him. He says he'll surrender, but Holmes will only know why he did it if he plays along. Holmes is later saved by Watson taking a shot that breaks a window.
- Hope killed his first victim in the story using the same method; a choice between two pills, one of which is lethal. The show's Hope offers Sherlock this choice in a school, which is where the story's Hope stole the poison from in the first place.
- One of the victims scratches RACHE into the floor with her fingernails. In the original story, this was in blood, written by Hope, and Sherlock notes that the killer has long fingernails.
- The Navigator: Sherlock has all the streets of London memorized and can predict a cab's likely path and come up with an intercept course in a matter of seconds.
- Never Suicide: What look like suicides turn out to be the work of a Serial Killer, albeit one that makes his victims kill themselves (by telling them they will be shot, unless they take the 50:50 chance on survival by choosing between a poisoned and harmless pill) rather than killing them himself.
- No Good Deed Goes Unpunished: Two of Beth Davenport's colleagues took her car keys from her handbag on her birthday so she couldn't drink and drive. Unfortunately this meant she also had to take a cab, and the one she took had Jeff Hope as the driver. Without realising it, her colleagues accidentally condemned her. Although, had she driven drunk, she could well have died anyway.
- The Nose Knows: Sherlock is able to detect that two different people are wearing the same deodorant.
- Nothing Exciting Ever Happens Here: A variant; John says "Nothing ever happens to me" to his psychologist's suggestion that he blogs everything that happens to him. Then a couple of scenes later, he meets Sherlock...
- Not Now, Kiddo: Sherlock to Mrs Hudson, regarding the taxi. He has much bigger problems than a taxi he didn't order, thank you!
- Not That There's Anything Wrong with That: After Sherlock declines having a girlfriend, John asks him "Do you have a boyfriend? Which is fine by the way." Sherlock answers simply "I know it's fine." and keeps staring unmovingly at John, needing another repeated prompt to actually answer "No." to the question.
- Only a Lighter: Sherlock confronts the cabbie who's been forcing people to play a deadly game of picking one of two pills to see which is poisoned or he'll just shoot them. Sherlock picks the gun, which turns out to be a lighter. He comments that he knows a real gun when he sees one.
- On Second Thought: Sherlock insists that he's not in shock and doesn't need a blanket. Then his chain of deductions lead him straight to John being the one who shot Jeff Hope. He dismisses everything he's said up to this point as the after-effects of shock.
- Open Mouth, Insert Foot:Stamford: I heard you were abroad somewhere getting shot at- what happened?John: ... I got shot.
- The Password Is Always "Swordfish": A woman uses the name of her stillborn daughter as a password.
- The Perfect Crime: A serial killer makes all his murders look like suicides.
- Poisoned Chalice Switcheroo: The serial killer has two identical pills, one poisonous and one harmless, and forces his victims at gunpoint to choose one while he takes the other. Sherlock realises the gun is fake and is about to simply walk away, but the killer challenges him into playing anyway. However, before they can actually take the pills, Watson shoots him, and he never finds out which was which (although we can presume that the forensics team will take the two pills and do a forensic analysis to determine this).
- Power Walk: The last scene has Sherlock and Watson walk away in slow motion with confident looks on their faces.
- Preemptive "Shut Up":[Silence]
Sherlock: Shut up.
Lestrade: I didn't say anything.
Sherlock: You were thinking. It's annoying.
- Red Herring:
- The taxi passenger, who has a strong alibi of being new to the country.
- This episode does a great job of making you think that the sinister, all-controlling gentleman who calls himself Sherlock's arch-enemy, and who Sherlock tells John is the most dangerous man he'll ever meet, is Moriarty. This false play culminates in this man noting that he and Sherlock are Not So Different, which makes perfect sense when we learn soon after it's actually Sherlock's brother Mycroft.
- Reinventing the Telephone: In the pilot, Mycroft contacts John by watching him on London's ubiquitous CCTVs and calling every public phone he walks by until he picks one of them up.
- The Reveal: The killer is the taxicab driver, and he got the victims to commit suicide by forcing them to choose between two pills at gunpoint (one harmless, one poison).
- Roof Hopping: Sherlock and Watson do this when pursuing a cab (aided by Sherlock's knowledge of all the traffic stops).
- Rubik's Cube International Genius Symbol: It's downplayed but in one scene we see a Rubik's Cube on Sherlock's desk. He never constant diversion after all.
- Say My Name:
- John shouts Sherlock's name when he realises that Sherlock is in another building with the murderer. It's muffled through a window, which lessens the impact, but the fact that there's a dramatic echo (as well as an appropriate choice in soundtrack) helps.
- And then... "MORIARTY!"
- Screw the Money, I Have Rules!: Mycroft tries to bribe John into spying on Sherlock. In true sociopathic fashion, Sherlock doesn't see a problem with this.Sherlock: Pity, we could have split the fee, think it through next time!
- Serial Killer: Picking people at random and killing them because "they don't think". He has a sponsor.
- Sherlock Scan: The episode contains three different types of scans to establish just how Crazy Awesome Sherlock is. Though in a bit of a departure from the usual trope, he's not always quite right — when he first meets Watson, he deduces that Watson has an estranged alcoholic brother named Harry who has recently left his wife. He's right about the troubled sibling relationship, the alcohol, and the break-up... but Harry is short for Harriet.
- When Sherlock and Watson go to a café to stake out the killer, they walk down Rathbone Street, London W1. Basil Rathbone played Sherlock Holmes in several late 1930s/early 1940s films.
- One address they pair visit is 22 Northumberland Street, which just happens to be right next door to a Real Life cafe called The Sherlock Holmes.
- Slut-Shaming: Holmes uses his Sherlock Scan to humiliate Donovan and Anderson by blatantly stating that they were sleeping with each other. In this case, the fact that Anderson was married was the main source of shame.
- Stranger Behind the Mask: The serial murderer turns out to be a random taxi driver, whose reason for killing the people he did had nothing to do with the victims themselves.
- Suicidal Sadistic Choice: The serial killer who apparently never directly kills their victims, but merely talks them into killing themselves... at gunpoint. However, there was technically a chance for them to survive the game.
- Take a Third Option: Double Subverted. Rather than play the killer's game, Sherlock decides to take his chances with the gun, which turns out to be a cigarette lighter, correctly deducing that the killer's MO is to outwit his prey, not simply shoot them dead and that the "gun" was merely persuasion. Free to leave of his own accord, Sherlock stands up to do so but then the killer manages to bait him into his game by asking if Sherlock had figured him out, to which Sherlock can't resist and ends up nearly taking the pill.
- The Taxi: The murderer turns out to be a cabbie who uses his taxi to cover up his victims.
- They Look Just Like Everyone Else!: The killer turns out to be an ordinary-looking cabbie.
- Throwing Off the Disability: Watson returns after being wounded in Afghanistan, now walking with a limp and cane. But, as pointed out by others, the limp and pain are not constant, and disappear when he is occupied with something dangerous, exciting, or curiosity-inspiring letting them conclude it's mostly psychosomatic. They are right, and during the first episode it happens more and more often for extended periods until the limp and the cane disappear entirely. We later learn that he was wounded in the shoulder, not the leg.
- Tomboyish Name: During his investigation of Watson's phone, Sherlock notices the name "Harry" on it. Turns out it's Watson's sister, Harriet.
- Too Dumb to Live: Sure, Jefferson, threaten Sherlock. Not like he has a friend who will kill you if you do it.
- Trouble Entendre: Played with for laughs; when John is driven to a secret location to meet a sinister gentleman who inquires after his friendship with Holmes and attempts to bribe him for regular updates on Holmes' activities, he becomes convinced by the man's manner that he's some kind of master criminal speaking in these ("I worry about him. Constantly"). Turns out, it's actually Sherlock's brother Mycroft, who was being entirely sincere and (for him) straightforward the whole time.John: So, when you say you're concerned about him, you actually are concerned about him?
Mycroft: [As if John's grown a second head] Yes, of course.
- Uncovering Relationship Status: John asks Sherlock if he has a girlfriend or a boyfriend. When Sherlock makes it clear that he's single, John replies "Right. Okay. You're unattached. Like me. Fine. Good."
- The Un-Reveal: Right when we are about to learn which pill was poisoned, John shoots the serial killer. Now we will never know.
- Wasn't That Fun?: Sherlock and John have an important one of these after a chase, as John realizes his limp actually is psychosomatic and going on Sherlock's little adventures makes him forget the pain. The moment doesn't last long.
- Weapon for Intimidation: The culprit threatens the eponymous detective with a gun. Before long, Sherlock has reason to call his bluff. It's a novelty lighter.
- Wedding Ring Removal: Sherlock is examining the body of the woman in pink, particularly her well-maintained jewelry and her dirty and tarnished wedding band, which he finds to be clean on the inside, meaning it was regularly removed, and leading him to conclude that she was a serial adulterer.
- Well-Intentioned Extremist: Jeff Hope. He was killing innocent people in a kamikaze murder spree that could have killed him too, but he wanted to ensure his children would be better off after his death, as for every life he took, money would be paid to his children.
- Wham Line: There's a brilliantly comical, subverted take on this trope, when Sherlock and John encounter the mysterious and ominous man who has introduced himself as Sherlock's arch-enemy.Mycroft: This petty feud between us is simply childish; people will suffer... And you know how it always upset Mummy.
- Xanatos Speed Chess: Used by the cabbie. When Sherlock realises the gun is fake and he can just walk away unharmed, the cabbie changes tactics and uses reverse psychology instead, convincing Sherlock to take a risk by appealing to his vanity.
- You're Insane!: Sherlock himself gets called a psychopath:I'm not a psychopath, Anderson, I'm a high-functioning sociopath. Do your research.