Laughing (Michael Tse Tin Wah) is supposedly an undercover police officer who has infiltrated a triad organization. However, before he became a police officer, Laughing was a member of the triads and worked for the big boss man No. 1 (Anthony Wong). No. 1 was very good to Laughing, and Laughing looked up to No. 1 as his elder brother. In order to strengthen his business and illegal activities, No. 1 arranges for Laughing to join the Police Force and become his mole to gather information about the plans and counter-plans for operations by the police.
Laughing graduated from Police Academy with outstanding results but before he was assigned to a post as a police officer, his "bad boy" image attracted the attention of the Head of District Anti-Triad Squad, Superintendent Sin (Yuen Biao) who arranges his assignment as an undercover cop to infiltrate the mob syndicate.
Laughing is now a "double" mole. No. 1 was happy with this turn of events as Laughing was assigned to infiltrate the mob of his triad rival sibling (Francis Ng). To further complicate the situation, Laughing falls in love with Francis's sister, Karen (Fala Chen).
How will Laughing contend with the law, the triad brotherhood, and his love affair? No matter which camp he sides with, he is doomed to be a traitor to the other. Which path will Laughing ultimately choose to follow?