Boris Karloff stars as a doctor who transplants the brain of a gangster into the body of a dying professor (both played by Stanley Ridges), then tries to get the convalescing professor to remember — with his new brain — where the gangster hid half a million dollars. Once they visit the gangster’s old stomping grounds, the memories come flooding back and the professor begins having Jekyll and Hyde episodes. By night, he starts killing off his old gang members, all of whom are also looking for the money. Meanwhile, Karloff tries to keep nosey officials and family members at bay.
I was never quite able to get past the ‘brain transplant’ part of this story, or how the professor physically changes into the gangster, presumably to keep the audience from getting confused. To the credit of the hair and makeup department, I never knew both characters were played by the same actor. But at the same time, it would have been more credible to keep the character looking the same during his ‘episodes,’ and just let Ridges’ acting do the heavy lifting. Karloff’s constant, clunky narration is another sore spot. The film is also advertised as starring both Karloff and Bela Lugosi, but don’t get too excited — the two horror icons never share a scene together, and despite second billing, Lugosi plays a character with very little screen time.