Paul Coriolos is a professor who seeks vengeance on the members of a jury who sentenced his son to death at the gallows, who he swore was innocent. The professor goes into his dark laboratory where he creates a creature out of a gorilla whom he trains to kill his enemies. Meanwhile, a newspaper reporter named Stanley Gordon and a detective named Murphy are both on the case of the murders. Gordon seeks to save Judge Webster and his daughter Anne who are both marked for death. Eventually discovering who is behind the murders, Gordon faces Prof. Coriolos and his simian henchman in a final confrontation.