Tai Fei discovers he has a son, and soon realizes that he is a triad member involved in the Tung Sing gang which deals in narcotics.

Tung Tung just graduated from the police academy, encountering a Vietnamnese assassin on his first day on work. Tung in order to break through obstacle in his mind decides to join SDU. Among the teammates, Coolman feels resentment toward Tung, which he doesn't understand. Later he discovers Coolman is actually his step brother. Tung actively tries to get close to Coolman, but is rejected. When training reaches its last stage, Coolman and Tung's team reencounters the Vietnamnese assassin on a deserted island.