Elementary school teacher Sun Lu has always lived by the rules. But a routine home visit unexpectedly brings her into the life of Chen Xudong, the owner of a small aquarium shop and a single father. She sees him as a troubled man, while he sees beyond her composed smile to the loneliness and quiet strength she keeps hidden. As their misunderstandings fade, the peaceful world of tropical fish draws them closer, and two lonely souls slowly find their way to each other.