Pretty Poison (1968)

Dennis Pitt, now in young adulthood, has been conditionally released from a psychiatric hospital, where he had been institutionalized for an incident that occurred when he was fifteen. Despite the doctors believing he to be rehabilitated in not suffering from the fantasies which dominated his life, Dennis is still required to check in with his case officer, Morton Azenauer, once a week. Azenauer will do whatever he can to help Dennis survive in the outside world. A year following his release, Dennis violates the conditions of his release by moving without telling Azenauer, thus missing his weekly check-ins. He moves to Winslow, Massachusetts where he has gotten a job at Sausenfeld Chemical Co., his boss, Bud Munsch, the company, and his acquaintances in town not aware of his history. In not being truly rehabilitated, Dennis believes the company is part of an alien conspiracy to poison the water supply, including openly discharging chemical waste into the local lake next to the plant. Dennis spends much of his time gathering photographic evidence to support his belief. He also becomes infatuated with seventeen year old high school senior Sue Ann Stepanek upon first sight. In his "investigative" work, Dennis is able to convince Sue Ann that he is a secret agent, she who he co-opts into those investigations as they begin a romantic relationship. However, as Sue Ann deals with what she considers her repressed life, she, in her own slightly off kilter mental state and using her relationship with Dennis, works toward her own agenda, leading to tragic consequences.