A mad scientist unleashes his master plan: to transform himself into a mutated walking catfish, and gain revenge on those who have spurned him. His plans go wrong, and he becomes tempted to kidnap a nubile young woman to similarly transform her so that he can breed.

After notorious New Orleans gangster J.D. Walker is murdered in the 1940s, his spirit remains restless for three decades, until a hypnotist's supernatural nightclub act allows him to take over the body of a mild-mannered law student and seek revenge on those who got him killed.