Laughing is formally a police undercover. However due to a drug trafficking case, Inspector Pan is hot on his trails. Before Laughing becomes a police undercover, he works under triad leader Yi. Yi treats Laughing as his own brother, however to protect his territory and illegal businesses, Yi instructed Laughing to join the police force and act as his undercover. Laughing is a high-flyer in the police academy. However he never got a chance to join the force because he is specially picked by Inspector Xian to be an undercover in the underworld syndicate. Hence Laughing becomes a “double-undercover”. Yi is happy that Laughing is allocated to the triad of his rival. To make his situation worse, Laughing falls in love with the triad leader’s sister, Karen. Justice, brotherhood and love, what will Laughing decide on? His decision will be a turning point in his life.