A serial killer mutates with a chemical inside a sewer, to become a monster made of human waste just as the FBI and police are onto him.

Mad scientist Dr. Stern is turning students into super-smart cannibalistic zombies, and the local cops are too busy chasing a sex fiend to stop the flesh-eating ghouls. Fortunately, Stern's nemesis, FBI agent Susan Hannigan, is on the case. As the ravenous monsters overrun the town, Hannigan tries to convince Stern's faithful assistant to reveal how to foil the crazed doctor's evil scheme.