Smart Girls Don't Talk (1948)

Linda Vickers gets mixed up with gambler Marty Fain. One of Fain's henchmen uses her car in a killing, and the police come around asking questions. Linda decides to indulge in a bit of blackmail. Her brother, "Doc', comes to town and disapproves of the company she keeps. Fain is wounded in a killing and 'Doc' helps him out. But "Doc' is shot, and Linda decides to cooperate with the police, with more dangerous consequences than she bargained for.