Story

Kirk and McCoy track down a Professor Crater and his wife – McCoy’s old girlfriend, Nancy – on a planet where they’ve been the only life. The planet is littered with ruins and has no salt in its environment. Crewmen keep dying, and it’s some monster to blame. The monster makes it on to the Enterprise, killing even more people until it’s discovered to be masquerading as both its victims and others it’s come across. Bones has to make a difficult choice between his Captain and his old flame. Read on…