Horror legend Boris Karloff (Frankenstein, The Old Dark House, The Black Cat) portrays a kindly doctor who seeks to cure a young woman of polio through injections of human spinal fluid. Of course, spinal fluid is difficult to obtain, particularly as the victim must be alive. When a circus ape escapes and breaks into Karloff’s home, he finds the solution to his problems—or does he? This creepy classic was directed by William Nigh (Mr. Wu, The Mystery of Mr. Wong) and co-written by Curt Siodmak (I Walked with a Zombie, The Wolf Man) and Richard Carroll (Five Came Back), with atmospheric cinematography by Harry Neumann (My Gun Is Quick).