Insoupçonnable" (2010) is a film by Gabriel Le Bomin which is showing on TV 5 Monde this month. Currently it doesn't have English title but the title means above suspicion.
It was pretty good. I didn't see 'that' coming. The actor Marc-André Grondin who played Sam was a bit weak I thought. But over all it was pretty good. It is totally above suspicion.
Synopsis: "Henri is convinced that Lise, his new young wife, truly loves him. He is also convinced that Sam, the witness at their marriage, is Lise's brother. It's a perfect set-up. Well, almost..." (TV 5 Monde)
Available this month on TV 5 Monde
DVD Availability Unknown