Diary of a Chambermaid (1964)

Celestine has a new job as a chambermaid for the quirky M. Monteil, his wife and her father. When the father dies, Celestine decides to quit her job and leave, but when a young girl is raped and murdered, Celestine believes that the Monteils' groundskeeper, Joseph, is guilty, and stays on in order to prove it. She uses her sexuality and the promise of marriage to get Joseph to confess -- but things do not go as planned.