After saving the passenger plane, criminal police Wu Yingxiong (played by Mark Chao) from the serious crime team became a star in the police circle and starred in various police promotional videos. On that day, Harbour City fell into a sudden crisis. A series of explosions broke out on major traffic routes such as the high-speed rail and the cross-sea bridge. In the process of pursuing the suspect, Wu Yingxiong teamed up with criminal police Chen Zhen (played by Lin Gengxin) from the Criminal Investigation Team of the Eastern District Bureau, and once again met the wanted criminal Xu Dafu (played by Huang Bo) who was forced to be a human bomb. It turned out that the mysterious organization named "Night Walker" kidnapped the families of wanted criminals such as Xu Dafu and forced them to act as human bombs to blow up all the passages leading to the outside world in Harbour City, turning Harbour City into an isolated city, in order to release the biochemical virus and implement the "Withered Grass Plan" to destroy the city. In order to rescue Xu Dafu's wife Du Xiaoqing (played by Guan Ying) and stop the Withered Grass Plan, Wu Yingxiong and Chen Zhen challenged the Night Walker with forensic officer Lan Xiying (played by Zhang Junning), Black Hawk team member Huang Shikai (played by Xiu Jiekai) and others.