Coupable (2008)
Directed by Laetitia Masson

Film Synopsis

Blanche Grandville is the most obvious suspect when her husband is found dead at their home.  At least this is what Louis Berger, the police inspector leading the murder investigation, believes.  The man who is hired to defend Blanche is Lucien Lambert, an ambitious young lawyer who sees this case as a stepping stone to much greater things.  Late one night, Lambert feels himself drawn to his client's house.  Here, he encounters Marguerite Marquet, a strange young woman who was both Grandville's cook and his mistress.  It turns out that Grandville was on the point of leaving his wife to embark on a new life with Marguerite, not long before he was killed.  It looks as if Lambert has stumbled across a motive for murder...