On the day of the founding ceremony of the People's Republic of China in 1949, Xiao Dali, who had just entered the city and was reorganized as the director of the public security police station, found that the primary school teacher Feng Jingbo was full of doubts. With the high vigilance of a soldier and the sense of responsibility of a public security soldier, he insisted on partnering with Feng and becoming his neighbor. He spent his whole life going through hardships and carried out a pursuit for nearly 40 years without regrets. The film is based on Zhang Ce's novel No Regrets Tracking.