Ten years ago, Zhao Haiyang’s mistake during a manhunt led to the death of his mentor, Xia Hui. Now, Zhao is the Deputy Director of Dongzhou’s Public Security Bureau, while Fang Cheng, a former colleague, returns to the city with innovative ideas for police reform. Tension arises as Zhao is skeptical of Fang’s methods, but the new techniques prove effective in combating a wave of modern crimes. Just as progress is being made, the killer from a fifteen-year-old case resurfaces, forcing Zhao and Fang to join forces to bring the criminal to justice while facing an unseen, powerful adversary.