The new film The Blue Room is based on a Georges Simenon detective story (which I have not read), though his chief detective, Jules Maigret, makes no appearance. Julien Gahyde (Mathieu Amalric, who  is also director and co-scenarist), a married man with a young daughter, has an affair with Esther Despierre (Stephanie Cleau), the wife of a fairly well-to-do pharmacist.  Both their spouses wind up dead, Delphine Gahyde (Lea Drucker) was definitely poisoned, and the pharmacist (Olivier Mauvezin) possibly so.

Hence there are two questions: whether the pharmacist was poisoned, and who was responsible for each poisoning, if there were two. However, this is at least as much a psychological tale as one of detection, and the  relationships of Gahyde with the two women in his life are at center stage  Did he really love his wife, or is he just feeling guilty for betraying her?

The trial jury comes to a conclusion regarding the guilt or innocence of the adulterous couple as to murder, but the film leaves plenty of room for uncertainty in this regard. The film is well-acted and pretty efficiently done. Certain musical effusions seem  excessive, however, and there are some sexually explicit scenes.