Yan Xin is an ordinary white-collar worker who prefers to have sexual relationships with different guys. Yun Fei is a stalker, for whom pursuing, taking pictures and prying into others' private lives is his biggest hobby. One day, Yun Fei becomes curious about Yan Xin and starts to follow him. During an encounter, Yan Xin meets a pervert and his physical safety gets threatened. After witnessing the encounter, what will Yun Fei do?