Paranoid parolee Dennis Pitt (Anthony Perkins) strives to fit into everyday life working at a chemical factory but soon comes to believe the company is purposely polluting the town's water supply. Befriended by an attractive high school drum majorette, Sue Ann Stepanek (Tuesday Weld), Dennis is delighted when she approves of his scheme to pretend to be a CIA agent in order to destroy the factory. The plan goes awry, and the hapless Dennis becomes a pawn in Sue Ann's own devious plot.