Shortly before he is to wed, millionaire John Willis is visited by Dr. Harry S. Blair, a psychiatrist who informs him that years before he was married to Nancy, John's wife-to-be, and warns him that she is mentally unbalanced. Blair then relates the following story: After a whirlwind romance in Florida, Blair marries Nancy and starts a psychiatric practice in New York. One day, artist Norman Clyde comes to his office and tells him that an innocent man is about to be executed in Sing Sing Prison and that Nancy is the cause of his unjust incarceration. A distraught Clyde then explains himself to a curious Blair: Three years before, Clyde meets Nancy, whose maiden name was Monks, when she enrolls in his art class. The moody Clyde soon falls in love with Nancy's honest charm and beauty. Nancy, a secretary, introduces Clyde to her boss, millionaire Andrew Bonner, and persuades Bonner to showcase Clyde's paintings at one of his private showings. To Nancy's delight, Clyde's painting, a depiction of the tragic figure Cassandra for which she modeled, wins first prize at the showing. The evening is perfect until an expensive bracelet is stolen from a guest, and Clyde later finds it in Nancy'…