- HD 1080
- Runtime: 70m.
- Status: Released
- 2
- Languages: en
- Country: United States of America
- Director: Arthur Lubin
- Stars: Stanley Ridges, Boris Karloff, Bela Lugosi, Anne Nagel, Anne Gwynne
- keywords: experiment, gangster, professor, murder, mad doctor, car accident, brain surgeon, hidden loot, brain transplant, hidden money
- Production_studio: Universal Pictures
- Slogan: A Reign Of HORROR... a man-made monster on the loose!
- The Black Friday is featured in the top rankings of 1940
- #19 in Top Crime Movies of 1940
- #6 in Top Horror Movies of 1940
University professor George Kingsley is struck by gangsters while crossing the street, leaving him with brain damage and one of the gangsters, Cannon, paralyzed. Kingsley's friend Dr. Sovac attends to both men, and when Cannon offers him a reward for aiding his recovery, Kovac transplants part of Cannon's brain into the dying Kingsley's skull, creating a dual personality.