Psychiatrist Evan Marshall is sent to investigate disturbing reports from an expeditionary team on a small planet.. and discovers that one of the team members has mutated into a radioactive humanoid whose touch is fatal and whose telepathy protects him from any attack.

A crook and a divorced wife are abducted from Earth to participate in a battle of life and death against two aliens. The stakes: the winners' planet will be spared while the other is destroyed as entertainment for the aliens responsible for the game.