In the most pure and imaginative years of her life, 13-year-old girl Xie Xinmei (Xu Jiao) spent her time in the mountains with her grandfather (Zeng Jiang). The quaint cabin and the quiet and charming night sky are the most distant and firm attachments in her memory. But one day Xiaomei finally had to leave here, and she returned to the city with her father (Yu Chengqing) and mother (Liu Ruoying). The bustling city is colorful, but it can't bring her a little sense of belonging and touching. Xiaomei has similar feelings to Zhou Yujie (Lin Huimin), a boy who frequently moves and transfers with his parents. Similar circumstances and moods bring them together and become best friends. One day, Xiaomei's parents choose to break up, and she finally decides to return to the mountains, taking her good friend Xiaojie to look up at the long-lost starry sky together... This film is adapted from the original work of the same name by the famous picture book painter Jimmy.