Chief inspector of Hong Kong’s Criminal Intelligence Bureau, Cheuk Hoi, is suspicious of his close colleague’s mysterious death. Adding to the enigma, he discovers that the five undercover agents who were in constant contact with his dead friend have all vanished.
After completing his three-year undercover mission, Xue Jiaqiang returned to Hong Kong to open a foot bathing shop and continue to collect intelligence. Zhang Jizi, chief inspector of the criminal intelligence section, suspected that Zhuo Kai had been thrown into the underworld after he was released from prison and carried out comprehensive surveillance on him. Jia Qiang and Zhuo Kai were involved in the organ trafficking case. Together with female undercover Dou Yaxi and Security Bureau investigator Wei zuoreng, they worked together to smash the group involved. The Security Bureau and the newly established security intelligence agency were invited to join Xu Tiantang to take over the work of the Criminal Intelligence Division.