Academy Award winner Joan Crawford stars as a woman found wandering the streets of Los Angeles. Taken to a mental hospital, she weaves a harrowing tale of insanity, murder and the passion by which she has become Possessed. Louise Howell's (Crawford) psychiatrist learns that she is a nurse hired to care for a dying woman and that she rekindled a former romance with her patient's neighbor, David Sutton (Van Heflin). But the suicide of her charge and rejection by the man she loves drive Howell to madness--and murder. Or do they? Is Howell's harrowing story true or the misperception of a deranged mind? And is Howell guilty of murder or an innocent victim of something far more sinister?