Lilith (1964)

Vincent Bruce (Warren Beatty) is an idealistic young war veteran who has just begun working as a therapist in a mental institution in his Maryland hometown. His first patient is a sex-obsessed schizophrenic named Lilith (Jean Seberg), who quickly becomes smitten with him. At first, Vincent maintains a strictly professional relationship, but eventually he falls for and seduces her. Their union, however, begins to take a heavy emotional toll on Vincent, especially when he begins working with Stephen (Peter Fonda), a troubled young man who has also fallen under Lilith's spell. Can Vincent regain his fading sanity before it's too late? Based on the novel by J.R. Salamanca.