Jean-Pierre, recently retired, is a hypochondriac.
Anne, his wife, cheats on him with a former office colleague.
His daughter Cathy, divorced and the mother of a five-year-old boy, lives with Philippe, a "nice" guy who Mathieu, Cathie's gay brother, calls "Brain-lite."
When JP discovers a small mark on his skin on his right hip, that Cathie is marrying "Brain-lite," Mathieu has been dumped because he hesitated to invite his boyfriend to his sister's wedding, and that Anne is cheating on him, the family equilibrium implodes.
Arguments, settling of scores, insults... JP, Anne, Cathie, Mathieu, and Philippe spare each other nothing.
Together, they go through a spot of bother.