Ahui (played by Chow Yun-fat), a veteran in the police force, is a playboy. With the protection of his father's former subordinate, Uncle Zhan (played by Huang Zhan), although Ahui cannot get a promotion in the police station, he also has a leisurely life. The arrival of the new police officer Cao Liang (played by Li Yuanba) broke all this. Cao's bold and even reckless way of handling the case caused Ahui to make a fool of himself. Although Ahui hated Cao Liang, he had to partner with Cao due to the order of his superiors. At the same time, the drug lord Luo Maosen (played by Xu Shaoqiang)'s subordinate Viper Bing swapped the drugs he traded and sold them privately, and Viper Bing's sister Donna (played by Li Zhi) cooperated in selling drugs. The brother and sister entered Hong Kong illegally and depended on each other, hoping to improve their lives through the drug business. Luo Maosen's gang murder attracted the attention of the police. Ahui and Cao Liang took over the case, and they soon got clues from Donna. Luo Maosen also discovered that Viper Bing had replaced the pillars, and for a time, Ahui and Luo Maosen started a competition for Donna...