Cast & Crew
Ghost hunter Agatha Brewster returns home to the United States and is met by news reporter Jeff Carter, who is doing a story about the disappearance of her brother, scientist James Brewster. Agatha learns from James's partner, Dr. George Randall, that James has not really disappeared, but has gone into hiding as a result of an experiment which turned him into an ape-man. James still has his human intelligence, however, and keeps himself locked in a cage with a gorilla in his secret laboratory at Springfield, the Brewster estate. Jeff is assigned a female photographer, Billie Mason, who accompanies him on his pre-arranged interview with Agatha at the mansion. During the interview, both Billie and Jeff hear cries that sound like a gorilla. When Billie later develops her photograph of Agatha, she sees the ape-like face of James in the background. George refuses to help James obtain the human spinal fluid which might restore his humanity, so James murders George's butler and obtains the fluid from his body, forcing George to inject him. The serum fails, but James is convinced that he merely needs a stronger dose. George flatly refuses to assist him again. With the help of his gorilla, with whom he can communicate, James goes on a murderous rampage to obtain more spinal fluid. Jeff and Billie become suspicious of the Brewsters after reading reports that ape hair was in the victims' hands. While they investigate the Brewster mansion, James tries to force George to inject him, but George angrily smashes the vial of spinal fluid. James attacks and kills George, and Agatha, who had rushed over to warn George, arrives too late to save him. Billie is abducted by James, who takes her into his secret laboratory, intending to draw her spinal fluid. However, the gorilla becomes territorial and attacks James. After killing the ape-man, the gorilla comes after Billie, but Agatha provides the police with the clue to the secret entrance to the laboratory, and the police kill the gorilla in time to save Billie.
Emil Van Horn
J. Farrell Macdonald
Barney A. Sarecky
Most spirits are honest, gentle and kind, and only want to bring happiness to humans. But a few are evil and, having been wicked in life, are wicked in death, and only haunt the scenes of desperate crimes, reveling in murder.- Agatha Brewster
An unnamed character who alerts "Jeff Carter" about "Brewster's" disappearance appears repeatedly throughout the film, and finally identifies himself at the end as the author of the story. The actor could not be identified from the print viewed. The above credits were taken from a British print, which was retitled Lock Your Doors.