Never Look Back (1952)

A female lawyer hears a knock on her door one night and discovers that it is an old boyfriend, whose current girlfriend has thrown him out, and he needs a place to stay the night.

She agrees to let him sleep on the sofa but he must leave the next morning. When he returns home he finds that his girlfriend has been murdered. His former lover agrees to defend him without telling the court that he spent the night with her. Complications ensue.