Bonjour tristesse: Teenager Luc lives with his mother Liliane and his little brother Paul in Paris, has to cope with the fact that his mother is a prostitute and practically raise his brother alone. Luc is disillusioned. One day, little Paul wants to phone his grandmother in Nord-pas-de-Calais, one thing leads to another and suddenly the whole family finds themselves in a holiday in northern France. For Liliane it means a reunion with her mother, for Luc and Paul the reunion with their grandmother. And then someday on the beach Luc gets to know Manu(el) who teaches him lessons in love, life, fun, teenagerhood and friendship.