Capt. Labesch (Rafael Bertrand) travels to a remote island to whip its drunken police force into shape and is horrified to learn of a powerful voodoo death cult. He's disturbed by their sacrifices to a shadowy priest named Damballah (Boris Karloff). But local landowner Carl Van Molder (also Karloff) is fascinated by the rites. When Van Molder's niece, Annabella (Julissa), is kidnapped, Labesch teams up with a local policeman (Carlos East) to rescue her and uncover Damballah's true identity.