Possessed

A woman wanders through Los Angeles, uttering little besides the name 'David' and drawing the attention of passersby. She is admitted to the hospital's psychiatric ward in a catatonic stupor, where a doctor begins questioning her. She identifies herself as Louise Howell and starts recounting her life in fragments.

In a memory sequence, Louise recalls meeting David Sutton, who plays Schumann for her. She longs to have a monopoly on him, insisting she wants exclusive access to his love. He does not reciprocate and eventually returns her home in a boat, telling her their relationship is over.

Louise takes a job as a nurse at the Grahams' lakeside home and begins caring for Pauline, Dean Graham's ill wife. Pauline is irascible and suspicious, insisting Louise is having an affair with Dean. Louise grows weary of the situation and dreams of leaving.

Police trawl the lake and Pauline's body is recovered. Dean claims she killed herself, and a coroner's hearing results in a verdict of accidental death. This event marks a turning point for Louise and the family.

Dean's oil business needs an engineer, and David returns to help; he is hired. Louise suspects he has another woman, though David denies it. The Grahams then take Louise with them to Washington, D.C., to care for Wynn.

In Washington, Louise begins to drink and looks strained. David tells her he is out of love with her, and she angrily slaps him. The encounter deepens the emotional rift between them.

Dean asks Louise to marry him, and she agrees, even though she says she is not in love with him. The arrangement ties her more closely to the Grahams' troubled household.

Louise visits Carol at college in an effort to win her approval, and a reconciliation develops between them. The wedding approaches, changing the dynamic within the family.

On the wedding day, the uninvited David arrives late and talks with the crying Carol, who recalls a long-ago request for marriage. Louise warns David away. Later, Carol invites David to a box at a piano recital, and Louise experiences a distressing recollection of David at the piano and leaves.

Back home, Louise endures a lengthy hallucination in which she confesses to killing Pauline. Carol says she will tell Dean, and Louise hits Carol, who tumbles down the stairs and dies. The sequence exposes Louise's unraveling mental state and the blurred line between guilt and reality.

Seeking help, Louise visits a doctor under a false name and is advised to see a psychiatrist, but she walks out. She asks Dean for a divorce, claiming Pauline hated her and implying she might be institutionalized and unstable.

During a vacation back at the lake house, Louise climbs to Pauline's bedroom and is confronted by Pauline's ghost, who taunts her with the suggestion to kill herself. Dean arrives and confirms Pauline is dead, and Louise confesses to having helped Pauline die. This episode deepens Louise's guilt and fear of exposure.

At a nightclub, Louise and Dean see David and Carol. Louise misleads Carol by claiming David wants her, while David warns that he could tell Dean about their past if he chooses to act. The confrontation underscores the stakes of Louise's deception.

David taunts Louise during their confrontation and hints at exposing their history. A doctor is summoned, and Louise retreats, only to sneak away to David and pull a gun, shooting him repeatedly in a fatal confrontation.

Louise awakens in the hospital and admits to killing David. The doctor diagnoses psychosis and delusions, describing a long and difficult recovery ahead, while Dean pledges his unwavering support to help his wife heal.