Kirk is carting around baggage from eleven years ago, when he failed to act as a cloud that smelled sweet, like honey, appeared and several were killed. The crew is extracting some incredible ore when Kirk recognizes that smell. Three red shirts are sent to investigate. Two are killed by the cloud and one is badly injured. The Enterprise is supposed to dock with the Yorktown to bring important medical supplies. All Kirk can think of is the power of that cloud which has reintroduced his biggest failure. The cloud sucks the red corpuscles out of the bodies of its victims. A young ensign, son of an old friend of Kirk's is enlisted, and fails, just as Kirk did, to kill the foggy entity. The thing travels through space and the issue becomes what can be done to stop it. Simple phaser fire doesn't work. Kirk now becomes psychologist and pursuer as he allies himself with the young man. It works pretty well.
