Notorious
(1946)

The film was nominated for 2 Academy Awards - Best Supporting Actor (Claude Rains), and Original Screenplay.

Alicia (Ingrid Bergman), the boozy daughter of a famous Nazi traitor, is recruited by a government agent, Devlin (Cary Grant), to spy on friends of her late father.  While waiting for the specifics of her assignment, Alicia falls in love with Devlin, but he, well aware of her past, remains distrustful of her.  When he is informed that Alicia is supposed to seduce Alex (Claude Rains), a childhood friend, he is at first reluctant, but in the end coldly informs her of her assignment.  Stung, she agrees, and begins a relationship with Alex, eventually marrying him.

She uncovers the plot of the Nazi sympathizers her husband is involved with, but she is eventually compromised and Alex realizes she is an American agent.  Alex and his mother decide to slowly poison her, to make her death look natural, for fear that her sudden death would bring the notice of his co-conspirators on their mistake.  Devlin's continued distrust of Alicia nearly gets her killed as he initially believes her when she attributes her illness to her alcoholism.  By the time she realizes she is being poisoned, she is too weak to escape.  Becoming worried when she doesn't show up to her meeting, Devlin finally goes to her house and finding her, confesses his love.

As he attempts to walk a severely ill Alicia out of the house, Alex and his mother discover them.  Devlin threatens to make a scene if they do not help him smuggle Alicia out in full view of Alex's 'friends'.  Afraid of arousing suspicion, Alex helps Devlin and Alicia out of the house.  But when they reach the car, Devlin locks the doors and refuses to take Alex with them.  Devlin and Alicia drive off towards the hospital, leaving Alex to the tender mercy of his suspicious comrades.

(In the deleted scenes, it is implied that Devlin and Alicia marry)

Thanks Mary C!