After working as an undercover in a triad for 8 years, Sheng (Nick Cheung) finally arrests the triad leader (Francis Ng) and resumes his duties as a police officer. However, life does not return to normal as he is faced with suspicions colleagues and even trailed by the investigations team. One day, he meets some triad members whom he has earlier befriended as an undercover. Sheng forced into a corner when asked to collaborate with them once again?