After convincing their sons-in-law to settle with them in Chinon, Claude and Marie encounter all their co-parents-in-law, while the entire family is about to celebrate Claude and Marie's 40-year wedding anniversary.

After convincing their sons-in-law to settle with them in Chinon (in Qu'est-ce qu'on a encore fait au bon Dieu? (2019)), Claude and Marie had disastrous visits in China, Algeria, Israel and Ivory Coast. With their 40-year wedding anniversary approaching, their 4 daughters decide to invite David's, Rachid's, Chao's and Charles' parents to celebrate together. Living with them proves to be a difficult task for the Verneuils. Finally, a German artist meets Marie and Ségolène and gradually becomes a problem for the family.