After losing his two-year-old son, Lei (Andy Lau) begins a fifteen-year-long journey in quest of his missing child. On the road, he comes across a young repairman, Zeng (Jing Boran), who was also kidnapped at the age of four. Agreeing to help each other’s cause, Lei accompanies Zeng to Chongqing to try to find his home, developing a fatherly relationship along the way.