Arthur (10) wakes up sad in the morning and is accompanied outside by his mother on his way to school. Shortly before that, he meets the moon child in the playground. She asks him to show her the world and Arthur walks with her through the city to a large meadow where their journey ends. Along the way, Arthur has explained the human world to her, which she knew nothing about, and in turn asked her existential questions about her, life and death. As the moon child has to leave, we learn what has happened to Arthur and he is left alone…