Peipei (Huang Yao), a 16-year-old female student from a single-parent family, lives in both Hong Kong and Shenzhen. She goes to school in Hong Kong during the day and lives with her mother (Ni Hongjie) in Shenzhen at night, frequently traveling between the two places. In order to fulfill her promise to travel with her bestie Joe (Tong Jiawen), for her own sense of existence, and for her ignorant affection for Joe's boyfriend Ahao (Sun Yang), her inner impulse is ignited, and "water passenger" becomes her other identity, and a youth story with a sense of "adventure" begins.