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.

传奇卧底薛家强归来，发现世界天翻地覆。昔日如师如友的搭档卓凯疑似变节，空降上司韦作荣作风强硬。敌友难分，关系错综，一场关乎每个人安危的对决，正愈演愈烈！