Sun Lu is a kindergarten teacher who does everything by the book, and quietly longs to break every rule she follows. A home visit takes her into the life of Chen Xudong, who runs an aquarium shop and is raising a child on his own. To her, he looks like a problem parent. He looks past her good-girl manner and sees the same stubbornness and loneliness he carries himself. Among the tanks and the quiet of his shop, the two of them begin to drift closer.