Astronauts keep going crazy and blowing up on their way back to the ground, and scientists can't figure out why. The latest astronaut to fall to this mysterious syndrome manages to contact his scientist superiors just before doing himself in; he alternates between pleas to "push the red" Self-Destruct Mechanism and violent urges to "Kill! Kill!" Finally the "red" is pushed, the astronaut is blown to shards and the scientists are still stumped.
Meanwhile, over in California, young med student Paul frolicks on the beach with his girlfriend when they happen upon the severed arm of the dead astronaut. Against his girl's wishes, Paul returns to the beach and takes the arm home with him (for what reason, we're not told). Soon, it becomes apparent to everyone (in the audience, at least) that whatever malediction had possessed the astronaut still possesses the arm, which promptly goes on a killing spree (said spree resulting in a grand total of ONE death). Paul himself is a prime suspect in the murder, but the two scientists arrive with their own theories. Then the mysterious murderous force begins to infect Paul as well, and he attacks a Malt Shop owner and his own girlfriend. After realizing what he's doing, Paul takes the hand out to a junkyard with the intent of destroying it, and between a fever of over 100 and some hungry cats, the evil is defeated... er, handily.
This film contains examples of:
- Brainwashed and Crazy: Well, not exactly brainwashed, but similar. Definitely crazy though.
- Clear My Name: While Paul does attack a couple of people during his "infection", he is not responsible for the single successful on-screen murder.
- Creepy Shadowed Undereyes: The alien horror produces this effect in its hosts when it infects them.
- The End... Or Is It?: The bumbling ambulance drivers somehow manage to lose the killer hand in the film's closing seconds.
- Eldritch Abomination: Only implied; apparently it's some evil alien spirit or similar that takes over astronauts and turns them into krazy killers. It's also contagious.
- I Cannot Self-Terminate: Because my body is being controlled by an alien energy being. Push the red!
- Jurisdiction Friction: Invoked by the sherriff, but all the scientists want is the severed hand. And a little cooperation from the long arm of the law.
- Kill 'Em All: The malevolent entity has this as its raison d'etre.
- Like an Old Married Couple: At one point Paul and his girl argue over whether she should have brought her swimsuit on their date; their friend suggests their love is indeed true; "You two sound like a married couple already!"
- Organ Autonomy / Evil Hand: The astronaut's severed arm, still possessed by the Eldritch Abomination, is capable of independent perambulation and attack.
- People Puppets: The astronaut in the first scene and, later, Paul.
- The Scourge of God: The only victim of the killer hand (or any of its People Puppets) to actually die is the booze-and-pill-fueled landlady.
- Those Two Guys:
- The bumbling ambulance drivers.
- Also the two scientists, Peter Breck and Faux-Gordon.
- Too Dumb to Live: And why, pray tell, is Paul so dead-set on bringing that severed arm home with him? For Science!?
- Troll: Invoked; in an early scene, Paul's Swedish girlfriend notes playfully how she is soon to return home. After he has been accused of murder and is about to run away, she tries to snap him out of it by admitting that she had only been teasing him about going home.