Delphine has two sides in her life. During the time she is a devoted activist volunteered to exchange letters with prisoners. In the night she attends ‘sex lessons’ performed by Prof. Christophe. One day, Frank, one of the inmates she replaced letters, is released. He begins residing with her and her roomie Angella. Christophe seems uneasy about it.

Marianne tells Paul that she is leaving him for Mathieu. Then, Mathieu's wife comes to see Paul and ask to help her to take revenge of the infidels. For that, she says they have to simulate to be in love to each other. Paul agrees to play the game ...