After his dear friend Professor Kingsley (Ridges) is nearly killed in a gangster hit-and-run, esteemed surgeon Dr. Ernest Sovac (Karloff) saves his colleague's life by performing a partial brain transplant - using the gray matter of infamous underworld thug Red Cannon.

But soon after the operation, Sovac discovers that, prior to his death, Cannon had stashed away $500Gs from a recent bank heist. With Cannon's brain now in Kingsley, will the good professor somehow be able to recall the whereabouts of the stolen loot?

Occasionally hampered by an overcooked script from Universal horror screenwriter Kurt Siodmak (1941's The Wolfman and 1944's The Climax, among many), this warrants a late nite watch thanks to its bonafide star power and some decent Jekyll and Hyde sequences from Ridges.