The Locket (1946)

Lovely Nancy seems like the ideal bride to fiancée John Willis... until, just before the ceremony, Willis is approached by Harry Blair, claiming to be Nancy's former husband. The tale Blair unfolds (in a flashback within a flashback within a flashback!) paints Nancy as a kleptomaniac, habitual liar, and perhaps worse. But is Blair telling the truth? And does fate have another surprise in store?