In the third year of the Huangyou era of the Song Dynasty, in Sishui County of Zhuojun Prefecture, a large number of people went missing, causing public resentment and leading to a rebellion. Although County Magistrate Zong Chao suppressed the uprising, the lost population could never be recovered. The Ministry of Justice sent undercover agent Qiu Xinzhi, under the orders of Grand Commandant Lu, to replace the assassinated leader of the Sishui Gang, Zhou Guang, and to gather intelligence under his undercover identity to investigate the missing persons case. Qiu Xinzhi, relying on his resemblance to Zhou Guang, infiltrated the Sishui Gang, constantly feeling the threat of assassination looming around him. As expected, shortly after he began his investigation, he was attacked, leading him to team up with the openly working investigator Xiao Liyuan to solve the case. However, due to the complexity of the case and Qiu Xinzhi's unconventional and reckless methods, which felt like randomly swinging punches, made solving the case a headache for Xiao Liyuan. After facing numerous dangers, the case was finally solved, but Qiu Xinzhi chose to abandon his original identity and continue his undercover career, embarking on the journey to uncover new cases.