The <i>Enterprise</I> is heading for Space Station K-7 and Kirk is testing Chekov on his knowledge of the system. The Klingons are contesting the nearby space, particularly Sherman’s Planet, but whoever can develop it the best gets the planet under the Organian Treaty. They’re interrupted by a Priority One distress call, indicating near-total disaster.
The ship goes to red alert and approaches the station, but there’s no signs of disaster. They make contact with Mr. Lurry, the station supervisor, who invites them over to explain. Kirk and Spock beam over and meet with Nilz Baris, the Undersecretary in charge of agricultural matters in the sector. Baris demands that the <i>Enterprise</i> guard a shipment of quadrotriticale, the only wheat that will grow on Sherman’s planet. Baris and his assistant, Arne Darvin, insist that Kirk take the matter seriously as Klingons may attempt to sabotage the shipment, while the captain is less then thrilled to be guarding grain. Kirk reluctantly complies with only two security guards, and also orders shore leave.
Chekov and Uhura arrive on the station and go to the bar, where pilot Cyrano Jones is dealing with the local trader and trying to sell him a small furry creature known as a tribble. Uhura is taken with the tribble and Cyrano Jones gives her one for free, and they notice that it’s eating Chekov’s sample of quadrotriticale. Cyrano Jones ends up making the sale.
Admiral Fitzpatrick call from Starfleet and informs Kirk that the safety of the grain is paramount. After he signs out, a Klingon ship arrives and Lurry contacts Kirk to inform him that Koloth and his lieutenant are already aboard. Kirk and Spock beam over and Koloth demands shore leave under the terms of the treaty. Lurry defers to Kirk who grants Koloth the leave but insists on having each Klingon accompanied by one security guard.
Later in the ship’s mess hall, Kirk comes in and discovers that Uhura’s tribble has bred. McCoy asks for a specimen for analysis and Uhura gives away the rest of the litter. Baris calls Kirk to express his displeasure with the Klingons on board K-7, and Kirk takes refuge in Sickbay, where McCoy informs him that the more you feed a tribble, the faster it breeds.
On board the station, the Klingons are in the bar and react badly to the tribbles and vie versa. Scotty, Chekov, and Ensign Freeman are taking shore leave when Koloth’s lieutenant Korax tries to provoke a fight by insulting the crew and the captain. Scotty tells Chekov to avoid fighting… until Korax insults the <i>Enterprise</i> Scotty then slugs Korax and a fight breaks out. Security breaks up the fight and Kirk demands to know who started the fight. Nobody admits to knowing who threw the first punch, and Kirk confines them all to quarters. He confronts Scotty who finally admits that he through the first punch, but only because Korax insulted the ship. Scotty ends up confined to quarters, and thrilled at the thought of catching up on his technical journals.
Upon arriving on the bridge, Kirk discovers that the tribbles have multiplied even more and he calls a meeting with Cyrano Jones. Jones professes innocence and after he leaves, Nilz Baris and Arne Darvin arrive to accuse Jones of being a spy. Spock says there’s no indication he’s working with the Klingons and Kirk dismisses Baris’ complaint.
Back on the <i>Enterprise</i>, Kirk and Spock find the ship inundated with even more tribbles. Realizing they’re into the food vents, Kirk and Spock beam over to the grain bins on K-7 and Kirk manages to get the hatch open… only to have thousands of tribbles fall on him. The tribbles are gorged on the grain, and Baris is furious at Kirk treating him and the project with contempt. McCoy arrives to announce that if they quit feeding the tribbles, they’ll stop breeding. Spock notices that many of the tribbles are dead, and McCoy confirms that even more are dying. McCoy goes to determine why the tribbles are dead, and Kirk calls a hearing.
At the hearing, Koloth demands a formal apology for his treatment and Nilz Baris is concerned that it will cost them Sherman’s Planet. Koloth asks that they remove the tribbles from the room, but as the security guards take them out they react to Arne Darvin as he arrives. Kirk confirms the tribbles react badly to only Klingons… and Arne Darvin. McCoy scans him and confirms that he’s a disguised Klingon agent. McCoy also confirms that someone poisoned the grain with a substance that cause a blockage of the digestive system, so that the tribbles starved to death. Kirk confronts Darvin with the tribbles and convince him to confess. Kirk tells Koloth to leave right away then deals with Cyrano Jones, telling him to pick up every tribble before his ship is released. Jones has no choice and starts cleaning up the tribbles.
The <i>Enterprise</i> leaves the station and there are no tribbles aboard. Kirk tries to get an answer to where they all went, but no one wants to explain what happened. Finally, Scotty is forced to admit that he used the transporter… and beamed them all over to the Klingon ship. Share this article with your friends