Thelma Jordon, late one night, shows up in the office of married Assistant DA Cleve Marshall. Before Cleve can stop himself, he and Thelma are involved in an illicit affair. But Thelma is a mysterious woman, and Cleve can't help wondering if she is hiding something. Thelma has a plan up her sleeve that will ruin Corey if his love for her and his own weakness win out. Thelma has a heart and a conscience. She comes to love Cleve, and has concern for his life and his future.