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.
Stanley Ridges
as Prof. George Kingsley / Red Cannon
Boris Karloff
as Dr. Ernest Sovac
Bela Lugosi
as Eric Marnay
Anne Nagel
as Sunny Rogers
Anne Gwynne
as Jean Sovac
Virginia Brissac
as Mrs. Margaret Kingsley
Edmund MacDonald
as Frank Miller
Paul Fix
as William Kane
Murray Alper
as Bellhop
Jack Mulhall
as Bartender
Raymond Bailey
as Louis Devore
Joe King
as Chief of Police
