During a space flight to Saturn, three astronauts are exposed to a radiation blast that kills two and gravely injures the survivor, Colonel Steve West [Alex Rebar]. Back on Earth, West wakes in a hospital to a horrifying sight: the flesh on his face and hands is melting away, triggering a panicked assault that ends with him killing a nurse [Bonnie Inch] and fleeing into the night.
Doctors Dr. Loring and Dr. Theodore “Ted” Nelson [Burr DeBenning] quickly realize the nurse’s body is emitting faint radiation, and they determine that West’s own body has become radioactive. Nelson hopes the diagnosis isn’t a sign of madness and theorizes that West might need to consume human flesh to slow the decay. He contacts General Michael Perry [Myron Healey], an Air Force officer familiar with the accident, and Perry agrees to help locate West.
West’s rampage continues in the woods, where he kills a fisherman and then encounters a young girl, Carol [Julie Drazen], whom she manages to flee from unharmed. Nelson and Perry arrive at the crime scene, and Sheriff Neil Blake [Michael Alldredge] suspects Nelson knows more than he’s admitting. Nelson remains tight-lipped, insisting that information about West remains classified. That night, Nelson returns home to his pregnant wife Judy [Ann Sweeny], only to learn that Judy’s elderly mother Helen [Dorothy Love] and Helen’s boyfriend Harold [Edwin Max] are on the way for dinner. Tragically, West appears along the way and kills Helen and Harold.
Blake confronts Nelson, who finally reveals West’s condition. Nelson posits that the decaying body might paradoxically grow stronger as the melting progresses. Back at Nelson’s residence, West attacks and kills Perry, while Judy is not harmed. Nelson and Blake materialize just as West escapes again. The chase leads them to the home of a married couple, where West slaughters the man and assaults the wife; she defends herself by severing West’s arm with a cleaver and driving him away. Blake contacts Nelson, and the investigators pursue the mystery.
Their trail ends at a colossal power plant, where Blake attempts to shoot West with a shotgun. West repels the attack by hurling Blake into live power lines, killing him. West then knocks Nelson over a railing, leaving the physician hanging in danger. Nelson pleads with his former friend, reminding him of their shared history, and West, in a moment of doubt, pulls Nelson to safety. Two armed security guards arrive, and in a panic, fatally shoot Nelson in the face as he strives to shield West. Enraged, West kills the guards and stumbles away, exhausted and enraged.
Collapse comes against the side of a building, and West slowly, completely melts away. The following morning, a janitor [DeForest Covan] discovers the gruesome remains and casually sweeps them into a garbage can. The news outlets celebrate the prospect of humanity’s next venture to Saturn, as the world moves forward with renewed ambition even as one man’s fate serves as a stark reminder of the unknown dangers that lie beyond our reach.
