Brain specialist Dr. Sovac illegally transplants part of injured gangster Red Cannon's brain into the head of his dying friend Professor Kingsley. The operation saves Kingsley's life but transforms him into a Jekyll-Hyde. When Dr. Sovac discovers the dead gangster had hidden away $500,000, he is determined to locate the money through the part of Red's brain that still lives. © 1940 Universal Studios. All Rights Reserved.