Born to Kill (1947)

Living in a Reno boardinghouse while awaiting her quickie divorce, Claire Trevor discovers the body of one of her roommates along with that of the roommate’s suitor. Instead of calling the police, she hightails it to her sister’s home in San Francisco, followed by the killer, a private investigator, and the boardinghouse’s suspicious matron. The assumption might be that Trevor is simply a woman in the wrong place at the wrong time, but it’s soon apparent that she’s not going to be playing the victim. It’s an incredibly dark noir where there doesn’t seem to be a single character of quality and loyalties are discarded and picked up again at the drop of a hat.