While engaged in a bizarre evolutionary experiment, scientist Jonathan Brewster (Bela Lugosi) is transformed into a hideous ape creature. Desperate to reverse the process, Brewster must acquire human spinal fluid. With his murderous gorilla henchman in tow, the pair sets out on a killing spree in an effort to affect a cure. Living up to his reputation for economical directing methods, director William Beaudine delivers a classic of the horror genre with often surreal comic overtones. The mysteriously psychotic Lugosi character combined with the "special effects" that only a costumed gorilla can deliver, make for a thoroughly entertaining hour of oddly seductive cinema.