Dr. Bernard Adrian is a kindly scientist who seeks to cure a young woman's polio. He needs human spinal fluid to complete the formula for his experimental serum. Meanwhile, a vicious circus ape has broken out of its cage, and is terrorizing the townspeople. Can there be a connection?
Boris Karloff
as Dr. Bernard Adrian
Maris Wrixon
as Frances Clifford
Gene O'Donnell
as Danny Foster
Dorothy Vaughan
as Mother Clifford
Henry Hall
as Sheriff Jeff Halliday
Selmer Jackson
as Dr. McNulty
Gertrude Hoffmann
as Jane the Housekeeper
Jessie Arnold
as Mrs. Brill
Billy Bletcher
as Short Mustached Posse Man
Harry C. Bradley
as Quinn
George Cleveland
as Mr. Howley
Ray Corrigan
as Nabu
