The Eunice Corporation is on the ground floor of an exciting industry--memory resculpting. It envisions nationwide clinics where anyone can lose the hang-ups of an unhappy childhood, a failed romance, or a botched career. Dr. Rex Martin (Bill Pullman) is employed there as a neurologist who is trying to find the part of the brain that causes paranoia. He performs an experimental operation on John Halsey (Bud Cort)--a mathematician who went crazy and murdered his family--which eliminates Halsey's paranoia, but once the operation is compete, it appears that the madness has taken over Martin's psyche. Martin then finds himself in an asylum experiencing hallucinations from Halsey's point of view.