Two detectives investigate the strangulation murder of a man whom everyone seemed to like.

The arrival in a small mountain town of a dissheveled stranger launches a series of murders committed by some sort of animal. As the town doctor and his daughter attempt to help the stranger, the sheriff investigates the murders; and they uncover a sinister experiment involving two rogue scientists, a car accident victim, his wife and children, and a serum that causes a man to turn into a ravaging werewolf.

A police detective baits killer gamblers with a mob witness (Patricia Medina) in the Everglades.