Stéphane Petitbourgeois is having trouble with his son-in-law Hubert, who has an extra child every year and is expecting his ninth, making thirteen people in the same apartment. However, a competition promises twenty million to the youngest grandfather of twelve grandchildren. Stéphane begins to encourage Hubert. But Pat became sterile from that day on. Finally, after two years, a child is announced. In fact, triplets were born, and after a few twists and turns, Stéphane became the youngest grandfather of twelve grandchildren.

Cast

Jane Sourza

Isabelle Petitbourgeois, la femme

Raymond Souplex

Stéphane Petitbourgeois, le mari expert-comptable

Louis de Funès

Célestin Ratier, représentant des industries de l'enfance

Jean Carmet

Hubert, le beau-fils

Andrée Servilanges

Geneviève, dite Mademoiselle, la nurse

Andréa Parisy

Pat, la fille

Florence Blot

l'employée de l'état civil

Saint-Granier

lui-même

Marthe Alycia

Daphné, la mère d'Hubert