"While working on a jungle plantation in South America, Barney Chavez (Raymond Burr) begins an affair with his employer's beautiful wife, Dina Van Gelder (Barbara Payton). When a native witch sees Barney murder his boss, she places a curse on him that transforms him into a gorilla each night. With a dangerous beast on the loose, police commissioner Taro (Lon Chaney) is called in to investigate -- and put an end to the terror."