A case involving a university student in 2006 has remained unsolved due to lack of evidence. The victim's boyfriend, Lian Zhou, refuses to give up his search for the truth in spite of everyone's objections. He moves to the city where his girlfriend was last seen and makes gas tank deliveries as a cover. Through the course of the investigation, Lian Zhou forges a friendship with detective-in-charge Fu Xiang and they work together to find the culprit.