In Miami, Florida, biker gang leader Edward "Diablo" Santer is about to be executed for murder when he proclaims his innocence and vows revenge from the grave. When a mysterious biker comes to town during Spring Break festivities, leaving several teenagers electrocuted to death, some begin to suspect that Santer has made good on his promise.

A scientist at a Florida university inadvertently creates a "rage virus" while performing experiments intended to restore dead brain tissue in baboons. When a journalist for the college paper breaks into the campus lab, he's bitten by one of the infected baboons; the virus soon spreads to a trio of rapists and a valley girl, all of whom go on killing sprees.