 The Enterprise is called by urgent distress signal to a space station where a federation official insists they take charge of security of a supply of a special grain destined for Sherman s planet, which is also claimed by the Klingons, who arrive soon  for shore leave  (managing to have a brawl with Enterprise crew after insulting Kirk and, what even gets to Scotty, the highest-ranking officer present, the ship), a line of work Kirk has a hard time taking seriously but is ordered by an admiral. While some crewmen go on shore-leave they pick up a pet put on the market by space peddler Cyrano Jones: the tribble, a fur ball which eases human nerves and proves excessively fertile, causing Kirk even more stress, which only grows worse...