Arthur es un hombre de unos 40 años con una edad mental de unos 6. Aún vive en casa con su madre Birthe, quien se encuentra en su lecho de muerte. Birthe lo es todo para Arthur, y ahora que está gravemente enferma, Arthur se ve sumido en una incertidumbre que le cuesta gestionar. Arthur pasa sus días recogiendo basura o viendo películas viejas una y otra vez. Un día, su hermana Petra lo lleva de compras y a él se le ocurre una idea para salvar a su madre.
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Arthur is a man in his 40s with a mental age of around 6 years old. He still lives at home with his mother Birthe, who is on her deathbed. Birthe is everything to Arthur, and now that she is seriously ill, Arthur is thrown into uncertainty which he struggles to navigate. Arthur spends his days collecting garbage or watching old movies on repeat. One day his sister Petra takes Arthur shopping and he gets an idea on how to save his mother.