The Enterprise escorts grain ships to Sherman's Planet, rescues Cyrano Jones from the Klingons and has to cope with his new, giant tribbles.
The Enterprise is escorting two robot ships of grain to the famine-hit Sherman's Planet when it finds a Klingon battlecruiser under Captain Koloth attacking a small scout ship. Kirk rescues the pilot, the trader Cyrano Jones, who has a new breed of supposedly non-breeding tribbles and a glommer, a creature the Klingons engineered to eat tribbles.
The Klingons disable the Enterprise with a new weapon and demand Jones, while some of the new tribbles grow enormous. McCoy finds that the giants are really colonies of smaller tribbles. The glommer is scared off, Kirk beams tribbles onto the Klingon ship, and McCoy slows the rest with a serum. David Gerrold wrote this sequel to his live-action story.