More Tribbles, More Troubles

The Enterprise is escorting two robot ships loaded with quintotriticale grain to Sherman's Planet, which is suffering a famine. When a Klingon battlecruiser under Captain Koloth attacks a small scout ship, Kirk beams the pilot aboard. It is Cyrano Jones, carrying genetically altered tribbles that he insists cannot breed, along with a glommer, a creature that eats tribbles. The Klingons, armed with a new weapon that drains a ship's power, want Jones handed over, and Kirk drives them off by having a cargo ship ram them. Meanwhile, the tribbles keep growing. Koloth reveals that Jones's tribbles have infested a Klingon world, and that the glommer was a Klingon creation Jones stole. McCoy discovers that the giant tribbles are really colonies of small ones and treats those aboard the Enterprise. Kirk returns the glommer, and when Koloth fires on a giant tribble, his ship is flooded with little ones.