1946 film by Tay Garnett

Helen Brent has just received a Reno divorce. That night, she discovers one of her neighbors, Laury Palmer, and a gentleman caller murdered in their home. The killer is her neighbor's other boyfriend, who won't abide anyone "cutting in" on him. This is Sam Wilde, a man who knows what he wants, is insanely jealous of what he has, and will kill to keep it. Rather than tell the police what she knows, Helen hops a train back to San Francisco...