Which is more dangerous, a Klingon Battle Cruiser, or a million furry pets clogging up the engines and eating valuable grain? Sherman's Planet is in dispute. The Federation wants it, but so do the Klingons. The Federation representative whose name is Nilz Baris, improperly uses emergency channels to call the Enterprise to the Space Station where the grain quadrotriticale is being stored. This is the only grain that will grow on Sherman's Planet. Kirk i outraged that his ship was summoned to guard a grain storeroom, but he assigns shore leave, because Baris does have the right on a matter of this importance. Baris' assistant, named Arn Darvin, and Baris himself, cannot believe how lightly Kirk is taking the importance of securing this planet. While the Enterprise is on shore leave, the Klingons arrive, and because this is a peaceful space station, they are allowed to take shore leave as while. Uhura has received a gift from a passing peddlar whose name is Cyrano Jones. It is a furry pet that purrs, and asks nothing, but gives love. Of course, it also eats a lot and has babies so quickly that soon there are dozen everywhere. Meanwhile the Kilingons and Federation crew get into a fist fight. Scotty threw the first punch when a Klingon called the Enterprise a piece of garbage. And now there are hundreds of these tribbles. McCoy discovers that they are "born pregnant", that their entire life cycle is geared toward reproduction. Kirk says "What the Hell" they rush to the space station, and yes, the tribbles got into the grain and ate it all. But wait, half of them are dead. How? Look Out, the grain was poisoned, so the tribbles did a good deed by finding out. Kirk suspects the Klingons. One thing. Tribbles don't like Klingons. They always shriek and shake around Klingons, and when Kirk puts the tribble near Arn Darvin, it shrieks. Wow. Arn Darvin is a secret Klingon agent. The Klingons are accused and banned, and the Federation wins the planet. What about the Tribbles? Well, Scotty beamed them all over to the engine room of the Klingon ship, where, he says "they'll be no tribble at all." Wow. All is resolved.