Brother Laughing is supposedly an undercover police officer who has infiltrated a triad organization. During a drug-trafficking operation he is caused by Superintendent Poon. Before he became a police officer, Brother Laughing was a member of the trads and worked for the big boss man No. 1. 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 who arranges his assignment as an undercover cop to infiltrate the mob syndicate. Laughing was 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. To further complicate the situation, Laughing falls in love with Francis' sister, Karen.