袁浩云（周润发饰）是一个嫉恶如仇极其讲义气，性格火爆反传统的神探。在一次行动中袁浩云的好友不幸遇难，他着急的想要报仇，但是上司为了案件顺利不让袁浩云继续调查，于是他只能自己去调查。江浪是一个混迹在非法走私军火集团的黑帮海叔的左右手，海叔想要把江浪培养成自己的接班人。海叔年纪很大，另一个新崛起的势力与海叔对抗，黑帮首领尊尼汪对江浪也很欣赏。江浪为了进一步掌握军火消息，干掉海叔证明自己对汪的忠心。汪高兴的把江浪纳入自己的阵营，成为第一马仔。袁浩云不知道江浪的卧底身份，但是在一次打斗过程中，马上就要被杀的袁浩云被江浪放过。后来，袁浩云知道江浪的卧底身份后，终于和江浪联系上，里应外合的破坏汪的犯罪集团

Yuan Haoyun (played by Zhou Yunfa) is a detective who hates evil, hates evil, is extremely loyal, has a hot personality and is anti-traditional. In an operation, Yuan Haoyun's friend was unfortunately killed, and he was anxious to take revenge, but his boss refused to let Yuan Haoyun continue to investigate for the sake of the case, so he could only investigate by himself. Jiang Lang is the right-hand man of Uncle Hai, a gangster who works in an illegal arms smuggling group. Uncle Hai wants to train Jiang Lang to be his successor. Uncle Hai is very old, another newly rising force confronts Uncle Hai, and the gang leader Johnny Wang also admires Jiang Lang. Jiang Lang killed Uncle Hai to prove his loyalty to Wang in order to get more information about the arms. Wang happily brought Jiang Lang into his camp and became the number one pony. Yuan Haoyun didn't know Jiang Lang's identity as an undercover agent, but during a fight, Yuan Haoyun, who was about to be killed, was let go by Jiang Lang. Later, after Yuan Haoyun knew Jiang Lang's identity as an undercover agent, he finally got in touch with Jiang Lang, and worked internally and externally to destroy Wang's criminal group