Although notorious New Orleans gangster J.D. Walker is shot and killed 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.

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.