Even though its title suggests otherwise, Petite Maman possesses an expansive quality. The narrative centers on Nelly (Joséphine Sanz), an eight-year-old who is grieving the loss of her grandmother (Margot Abascal). Nelly serves as our guide through the events unfolding, so there are times when we aren't entirely clear about what’s happening around her. Her grandmother died because of a long-standing illness, though Nelly doesn’t know its specific name. Accompanied by her parents—her mother (Nina Meurisse) and father (Stéphane Varupenne)—Nelly goes to her grandmother’s house to sort through her possessions. They stay for one night, but then Nelly's mother departs unexpectedly, leaving Nelly and her father to complete the task. The reason behind her mother's sudden departure isn't entirely clear, however, Nelly recognizes that her mother has been unhappy for quite some time, and she suspects her mother’s actions are connected to this sadness.

Source on TMDB