Recap / Star Trek S2 E15 "The Trouble with Tribbles"
And that's not the only bit of trouble on their hands.

Captain Kirk and Spock are quizzing Chekov about Deep Space Station K7 and the race to settle Sherman's Planet, presumably because Kirk knows nothing about the situation and Spock is bored of losing at 3D chess all the time. Midway through the quiz, however, a Priority One Distress Code is sounded, which surely means that the Klingons are invading Station K7's system by force. Racing to the bridge, Kirk orders the Enterprise to rush to the station as fast as possible.

Upon arrival, Kirk demands to know what the emergency is, and is informed that the undersecretary of agriculture, Nils Baris, is on the station and is scared of sabotage. Since Baris has the authority to issue the emergency call, Kirk can do little except speak in double and ask questions that should have been part of his mission briefing, like what exactly he is there to protect (the answer: a breed of hybrid grain called quadrotriticale; if it can grow on Sherman's Planet, the planet goes to the Federation, but if it can't, the planet goes to the Klingons, as it means nothing Earthlike can grow there). He authorizes two guards from the Enterprise to protect the grain, and begins shore leave for the rest of the crew. Shortly after, Captain Koloth arrives demanding shore leave for his crew. Kirk acquiesces, in part because the Organian Peace Treaty leaves him no legal reason to say no, and in part to piss off Baris.

Elsewhere on the station, Chekov and Uhura have been shopping and are taking a break in the station's bar when Cyrano Jones walks in, trying to sell useless crap to the bartender. This being the '60s, Uhura is immediately captivated by a purring ball of furnote  and buys it despite never having heard of the species before (apparently there is no rule against pets on the ship as Kirk has no objection until...) The tribble begins pewing babies out like mad, and the crews' first instinct is to pet and coo at the creatures, pausing just long enough to poo-poo Dr. McCoy at the thought of actually figuring out why the tribble population is increasing like Scotty's waistline.

Back in the bar, Scotty, Chekov, and another guy are trying to have a quiet drink when a drunk Klingon starts mouthing off about Captain Kirk. Chekov immediately wants to assault the Proud Warrior Race Guy but Scotty, remembering their orders to avoid trouble, keeps Chekov in line. However, Scotty throws the first punch after the Klingon makes a remark about the Enterprise, which leads to a brawl. Security restores the peace and the involved crew are dragged back to the ship. Scotty, rather than manning up and admitting the truth right away, gets the entire group confined to quarters.

Kirk, upon receiving his order of a tribble sandwich with a side order of tribble and a glass of tribble, deduces that the tribbles have likely also gotten into the grain storage on the station. Upon arrival, he stands immediately under the door that is theoretically holding back several metric tonnes of blue grain and opens the door. A flood of tribbles buries him armpit deep, prompting McCoy to make the startling discovery that reproduction is tied to metabolism. A lot of the tribbles are also dead, indicating that the grain was poisoned. Back in the station commander's office, Koloth confronts Kirk about the bar brawl before demanding that the tribbles be removed, since a tribble's purr sounds like a Paris Hilton karaoke to Klingon ears. As the guards go to leave, Baris's assistant, Arne Darvin, enters the office and has the same reaction to the tribbles that the Klingons have—and vice versa. McCoy scans Darvin with his tricorder and comes up with completely nonhuman results — "Jim, this man's a Klingon!" Since this makes him the prime suspect for the poisoning, Kirk arrests Darvin and tells Koloth to scamper off.

Back on the ship, Kirk is surprised to find that all the tribbles are gone. After some runaround, he is informed that Scotty beamed the tribbles about the Klingon ship "where they'll be no tribble at all." The crew joins in a hearty laugh as they most likely suppress the thought of what the Klingons are doing to the defenseless furballs at that moment. (It's later found it's the other way around, becoming "mortal enemies" of the Klingon Empire.)

This episode was lovingly revisited via Time Travel in the Star Trek: Deep Space Nine episode "Trials and Tribble-ations".

Tropes for this episode include:

  • Absentee Actor: George Takei (Sulu) was busy filming The Green Berets, so all his lines went to Chekov - this is why he knows about quadrotriticale, as a Call-Back to Sulu's interest in botany from "The Man Trap".
  • Accidental Hero: Lampshaded by Cyrano Jones.
    Jones: After all, my tribbles did put you wise to the poisoned grain, and they did help you to find the Klingon agent. You saved a lot of lives that way.
  • All Take and No Give: How Spock describes the tribbles:
    Spock: They are consuming our supplies and returning nothing.
    Uhura: Oh, but they do give us something, Mr. Spock. They give us love. Well, Cyrano Jones says that a tribble is the only love that money can buy.
    Kirk: Too much of anything, Lieutenant, even love, isn't necessarily a good thing!
  • Animals Hate Him: Tribbles emit a soft, purring sound around everyone except Klingons, who they react angrily to. This aids Kirk when he has to Spot the Imposter.
  • As the Good Book Says...: When Spock compares the Tribbles to lilies, he is referencing Matthew 6:28, which confirms that lilies indeed do not toil or spin.
  • Ass in Ambassador: Baris isn't technically an ambassador but he's definitely an ass. The only fun Kirk seems to get in this whole episode is at Baris' expense.
    Baris: Captain Kirk, I consider your security measures a disgrace. In my opinion, you have taken this entire, very important project far too lightly!
    Kirk: On the contrary, sir. I think of this project as very important. It is you I take lightly.
  • Bar Brawl: One breaks out between humans and Klingons.
  • Beleaguered Bureaucrat: Mr. Lurry, the manager of Deep Space Station K-7, who is caught up between Baris' demands, Kirk's impatience, the Klingons' requests and an infestation of tribbles.
  • Berserk Button: Insult all of humanity? Scotty will let it slide. Insult Captain Kirk? You have a right to your opinion. Call the Enterprise a garbage scow? Them's fightin' words! Also, Kirk doesn't like having his chicken sandwich and coffee ruined.
  • Blatant Lies: Spock comments on the tribbles: "Its trilling seems to have a tranquilizing effect on the human nervous system. Fortunately, of course, I am...immune to its...effect...", all while absentmindedly stroking said creature.
  • Bullying a Dragon: The drunk Klingon is going out of his way to insult whoever he can to get a rise out of the puny humans. When he finds out Scotty's pressure point is his beloved ship, the Klingon calls the Enterprise a garbage scow, then 'corrects' himself to say "that it should be hauled away AS garbage." The Klingon quickly finds out you do not enrage a Scotsman...
    • Even better: the Klingon takes on a Scottish burr after Scotty coolly asks him to "rephrase" his statement about his beloved Enterprise.
  • Butt-Monkey: Chekhov consistently winds up on the wrong end of the fight during the Bar Brawl with the Klingons.
  • Character Development: Interestingly one of the best episodes to allow each of the characters — Uhura, Scotty, and Chekov in particular — some nice development:
    • Uhura as a pet lover, being the one to bring tribbles aboard the Enterprise;
    • Scotty showing his trait of reading engineering journals as a means of relaxing;
    • Chekov getting a performance review as part of crew evaluations, and demonstrating some of the scientific background that pops up in later episodes.
  • Chekhov's Gun: The tribbles' reaction to Klingons ends up flushing out an imposter.
  • The Chew Toy:
    • The poor bartender is quickly overwhelmed by the tribble infestation. In his last scene, he's covered in tribbles with a silent, annoyed look on his face.
    • Kirk gets chewed out by Baris over nothing, learns that everybody— including Chekov— knows more about quadrotriticale than he does, has to tolerate Klingon visitors, gets his ship infested by tribbles, learns that Scotty considers it worth starting a bar fight over an insult to the Enterprise but not over an insult to Kirk himself, and gets buried in tribbles in what Deep Space Nine retcons as Sisko averting an assassination attempt that Kirk never becomes aware of.
  • Continuity Nod: Plays off the fact there's an "Organian Treaty" requiring the Federation and the Klingons to abide by Space Cold War rules of conduct, ranging from settling colonization claims to sharing station facilities.
  • Cool and Unusual Punishment: Cyrano Jones is given a most unpleasant choice of punishments: spend 20 years in a penal colony, or get the tribbles off the station, a task estimated to take 17.9 years.
  • Cuteness Proximity: Everyone (except Klingons) who gets close to tribbles.
    • Uhura in particular is absolutely adorable when she is introduced to the Tribbles and is offered one free of charge.
    Uhura: Oh I couldn't.......(pouty puppy dog face) could I?
  • Deadpan Snarker:
    • Spock is at his snarkiest in this episode. He tells Chekov that his little joke was "extremely little". He tells Bones that a tribble is as useful as an ermine violin. Bones continues to go on about their redeeming qualities, Spock offers one of his own; that unlike Bones they "do not talk too much". And then there's "He heard you; he simply could not believe his ears."
    • Even Kirk gets a bit snarky when Bones asks him what you get when you overfeed a tribble. "A fat tribble?" Kirk is also very snarky around Nils Baris; for example, when the tribble doesn't react to Baris in the same way it reacts to the Klingons, he remarks, "No accounting for taste."
  • Death Glare: Kirk shoots Bones a serious one while surrounded by tribbles. This is probably because Bones came in cheerfully telling Kirk that to stop their breeding all they need to do is stop feeding them. This is of little consolation to Kirk who is literally buried up to his neck in tribbles by this point.
  • Distress Call: The episode starts with one. Subverted when it turns out that it was sent by an Obstructive Bureaucrat who wants Kirk to guard his grain.
  • Early Installment Weirdness: The QuchHa' crew of the Gr'oth. These drunken fratboys are Klingons?!
  • Everybody Laughs Ending: "They'll be no tribble at all!"
  • Everyone Calls Him "Barkeep": Cyrano Jones tries to sell tribbles to Barkeep.
  • Evil-Detecting Dog: The tribbles don't like Klingons and the feeling is quite mutual. The tribbles even know when one is in disguise.
  • Explosive Breeder: The tribbles. They reproduce at will. "And brother have they got a lot of will."
  • Funny Background Event: While the fight is going on, Cyrano Jones takes advantage of the fact that the bar is left unattended to help himself to a few drinks.
  • Hidden Depths: When Kirk is giving everyone an impromptu tribble test and couldn't help but playfully observe:
    Kirk: But they do like Vulcans. Well, Mr. Spock, I didn't know you had it in you.
    Spock: Obviously, tribbles are very perceptive creatures, Captain.
    Kirk: Obviously.
  • The Hypnotoad: The tribbles again. The trilling noise has a soothing effect on humans. Vulcans are ... of course ... immune...
  • Hypocritical Humor:
    • After the tribbles have eaten all the grain on the station, Baris yells at Kirk for abusing his authority, among other things. This from the guy who made the galactic equivalent of a 911 call just to have Kirk guard his grain.
    • Spock describes the tribbles' "tranquilizing effect on the human nervous system", declaring "Fortunately, of course, I am immune to its effect."... while stroking a tribble and looking even calmer than usual. He then realizes what he's doing and puts the tribble down.
    • Scotty orders Chekov not to let the Klingons goad him into starting a fight. A few insults to the Enterprise later, Scotty himself is goaded into starting a fight.
  • Insistent Terminology: It's not wheat, it's quadrotriticale!
  • Irony: During the otherwise comedic episode, it turned out the Klingons poisoned the grain meant for a disputed planet with a toxin that blocks digestion. When the tribbles got into it, and died from it, Kirk described the situational irony thus, "In a room full of grain, they starved to death."
  • I Will Show You X: Kirk's reaction when Baris blames him for the apparent ruin of the Sherman's Planet project:
    Baris: You have abused your authority, and you've rejected my requests. And this, this is the result. I'm going to hold you responsible!
    Kirk: Mister Baris, I'll hold you in irons if you don't shut up.
  • Jack Bauer Interrogation Technique: Downplayed For Laughs—to a Klingon, tribble exposure might as well be waterboarding. It only takes a few seconds for Darvin to spill his guts.
  • Layman's Terms:
    Spock: Surely you must have realized what would happen if you removed the tribbles from their predator-filled environment into an environment where their natural multiplicative proclivities would have no restraining factors.
    Cyrano: Well, of cour—what did you say?
    Spock: By removing the tribbles from their natural environment, you have, so to speak, removed the cork from the bottle and allowed the genie to escape.
  • Lighter and Softer: Star Trek has its share of dark, tension-filled, Anvil-dropping plots. This is not one of them. Interestingly, this has made it one of the more popular episodes.
  • Living Lie Detector: Not by nature, but the tribbles are able to detect a Klingon posing as a human.
  • Ludicrous Precision: Spock's calculations on the number of tribbles breeding at any given time.
    • Shown Their Work: The calculations, assuming Spock's assumptionsnote  are entirely accurate; six generations of tribble reproduction would be around 11^6, or (as he puts it) 1,771,561.
  • MacGuffin Location: Sherman's Planet.
  • Meaningful Name: Writer David Gerrold named Sherman's Planet for his girlfriend at the time, Holly Sherman.
  • Not So Stoic: Even Spock likes the tribbles, much as he would deny it.
  • Now You Tell Me:
    Bones: Jim! I think I've got it. All we have to do is quit feeding [the tribbles]. We quit feeding them, they stop breeding.
    Kirk: (while buried in tribbles) Now he tells me.
  • Punch! Punch! Punch! Uh Oh...: Happens when Chekov tries to slug a Klingon in the gut.
  • Real Life Writes the Plot: In his book about this episode, David Gerrold said he got the line "A tribble is the only love money can buy" from a poster in a vet's office. The "fat tribbles" line was an homage to the "fat birds" line in Mary Poppins.
  • The Reveal: Nils Baris's assistant, Arne Darvin, is a Klingon.
  • Ridiculously Cute Critter: The tribbles!
  • Rule of Three: In a humor-filled episode, it's bound to pop up:
    Kirk: You'll do it?
    Spock: He'll do it.
    Cyrano Jones: I'll do it!
  • Running Gag: Everyone on the ship knows what quadrotriticale is but Kirk. Chekov "helpfully" points out that it's a Russian inwention.
  • Screw the Rules, I Make Them!: How Baris justifies summoning the Enterprise using a priority-one Distress Call that has an entire quadrant arming for possible war just for grain-protection detail.
  • Snark-to-Snark Combat: Spock v. Bones at its finest.
  • Spanner in the Works: The grain was poisoned in a way that would block the digestive system of those who ate it. This comes to light when the tribbles get into it, and before it could be shipped to Sherman's Planet.
    • The presence of the tribbles also reveals the presence of a Klingon spy, and thus the most likely person to have been involved in the poisoning.
  • Strolling Through the Chaos: Cyrano Jones during the Bar Brawl, complete with drink in hand. (He does dodge a Bar Slide at one point, but he's otherwise nonchalant through the whole thing.)
  • Suspiciously Similar Substitute: Koloth to Kor from "Errand of Mercy". Word of God wanted John Colicos to reprise the role of Kor both here and the later episode "Day of the Dove", but he was unavailable.
    • Also Chekov in for the missing Sulu, who as a botanist would be more knowledgeable about quadrotriticale.
  • That's an Order!: When Scotty is restraining Chekov from responding to the Klingon's insults, he says, "Don't do it, mister, and that's an order."
  • Tranquil Fury: "Laddie... don't you think you should... rephrase that?" (Laddie happily obliges.)
  • Truce Zone: As per the Organian Peace Treaty, Station K-7 is one. Naturally, the truce doesn't hold, especially with alcohol involved.
  • Unishment: Kirk "punishes" Scotty by restricting him to quarters — which suits him just fine, as he'll have a chance to finish the reading he was trying to do when Kirk made him go on shore leave. Kirk clearly realizes the pointlessness of this, since Scotty is almost immediately back out working again.
    • Given how Scotty is seen carrying a horde of Tribbles, odds are, Kirk had the brawlers put on Tribble clean-up duty.
  • Unwitting Instigator of Doom: Deep Space Nine reveals Scotty's joke of sending the tribbles home with Captain Koloth resulted in an ecological disaster for the Klingon Empire and the Klingons driving the tribbles to extinction.