After Dr. Walters (John Carradine) transforms an ape into the exotic Paula Dupree (Acquanetta), he then turns her loose at the circus. Paula fits in splendidly becoming an animal trainer who wields strange powers over her lions and tigers. She even falls in love with a fellow trainer though becomes overwhelmed with jealousy when she learns of his fiancée. Suddenly her human qualities disappear, turning her back into an ape -- and a killer.