The details of undercover police officers are deleted from a police database and a senior officer is left struggling to know who are the undercover officers and who are the criminals.
張家輝
as Blue
古天樂
as Shiu Chi-Long
吳鎮宇
as Q-Sir / Inspector Q
佘詩曼
as Ding Siu-Ka
許紹雄
as Foon Hei-Gor
陳豪
as Police Superintendent
張繼聰
as Triad Member
클라라
as Assassin
李光洁
as Tung Pak-Ho
Candy Chang Hui-Wen
as Siu Ying, Blue's Bodyguard
释行宇
as Sniper
成泰燊
as Kwok Ming
