Nocturne (1946)

Detective Joe Warne (George Raft) is investigating the death of a successful composer. While Joe's colleagues believe that the man killed himself, Joe isn't so convinced. After some poking around, Joe discovers that the composer was involved with numerous women (Lynn Bari, Virginia Huston), and many seem to have good reasons to want their former lover dead. Though Joe's superiors command him to stop investigating, he becomes so engrossed in the case that he will stop at nothing to solve it.