Giant robots from Venus invade Chicago. Stranded in the deserted city are Frank and Nora (who has recently attempted suicide). They meet a celebrating couple at a café, Vicki Harris and Jim Wilson. The quartet escape the robot patrol and take refuge in a large hotel. There, they encounter a new danger in Davis, a psychopathic killer.
Anthropologist Dr. Brockton unearths a primitive troglodyte -- an Ice Age "missing link": half-caveman, half-ape -- in a local cave. Through medical experimentation, she manages to communicate with him and domesticate him before he's let loose by an irate land developer and goes on a rampage, terrorizing the local citizenry.
A lady ringmaster milks the publicity from a string of murders.
Two crooks are hired to rob an eccentric old lady's estate, but once they get to know her, they can't bring themselves to do it.
