Laughing (Michael Tse), who presumably died during the events of E.U., used his death as a cover to perform a long term undercover mission in Dongguan, China. After completing his mission, Laughing returns to Hong Kong where CIB's senior superintendent, Harry Kung (Damian Lau), recruits him into his department to become team leader and teacher to new police recruits. On Laughing's very first day, he encounters a woman that greatly resembles his former lover, Karen (from Turning Point); she is Laughing's new commander and second lead in CIB, Senior Inspector Jodie Chau (both played by Fala Chen). Together, their assignment is to recruit and train rookies in the art of undercover and espionage. However, things do not go as smoothly as desired.