Decades after promiscuous teen Mary Lou Maloney (Lisa Schrage) dies during a prank gone wrong, she returns as a spirit out for revenge and eager to punish the culprit, her one-time boyfriend, Billy Nordham (Michael Ironside), who is now high-school principal. Evil Mary Lou is perfectly content to kill other locals, and she eventually possesses the body of prom queen contender Vicki Carpenter (Wendy Lyon), which allows her to wreak even more havoc.