Le Petit Bougnat (1970)

When the long awaited departure day arrives, le Petit Bougnat, a child coal merchant eager to go to summer camp, realizes that his mother forgot to register his name with the rest of the group. Desperate to join them, the young coal merchant tries to find a way to integrate himself with the other campers. On the opposite end of the spectrum is Rose (Isabelle Adjani), who refuses to join the kids and goes so far as to run away from the bus. While the coal merchant is busy avoiding authorities who want to remove him from the rest of the group, Rose continues to sulk and search for a way back home. Despite her initial doubtfulness, Rose eventually comes to see the charms of the camp, and walks away from an offer to leave.

Unfortunately the movie Le Petit Bougnat is not yet available on HBO Max.