Petite Maman is a movie about a girl (Nelly) who has just lost her grandmother and is helping her parents clean out her mother's childhood home. She explores the house and the surrounding woods. One day she meets a girl (Marion) her same age building a treehouse. They become friends and have all sorts of adventures together. As their relationship develops, Nelly realises that Marion is actually her mother who has travelled from the past to be with her. This is a surprise to both of them and themes of family, loss, and friendship are explored as they play together. The two actors playing the ...