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.

Gus Linden, former racketeer head of a Detroit local of the United Automobile Workers of America, A.F.L, attempts to destroy his successor, Blair Vicker, so he can put his old rackets back into the auto factories. Vickers fights him off, ultimately winning help from Linden's attractive daughter Barbara and from Joni Calvin, Vickers' moll.