On the day of the 1949 Founding Ceremony, Xiao Dali (Lei Jiayin), who has just entered the city to be reorganized as the head of the public security police station, discovers that Feng Jingbo (Hu Ge), an elementary school teacher, is suspected of being suspicious. With the high alertness of a soldier and the sense of responsibility of a public security warrior, he is hard-partnered with Feng Jingbo as a neighbor, exhausting his life through trials and tribulations, and carrying out a nearly four-decade tracking without complaint or regret. The movie is based on Zhang Ce's novel.