 Reinette and Mirabelle are two young girls. Reinette lives in the countryside, Mirabelle in Paris. They meet during a holiday of Mirabelle in the country, when Reinette helps her to repair the tube of her bicycle and shows her the beauties of nature and in particular the  blue hour . They like each other and decide to take a flat together in Paris, where they ll attend at the University. But isn t so easy to live together when the characters are so different: as Reinette is simple and enthusiastic, as Mirabelle is obscure and lazy.