陈星（陈星 饰）和嘉伦（梁嘉伦 饰）是童年时的好友，两人经常在一起玩“兵抓贼”的游戏，长大后嘉伦当了一名警察，而陈星则举家移民，两人再也没见过面。陈星和哥哥是阿姆斯特丹的毒品巨头，他们专做“跳灰”生意——毒品零售。一天哥哥遭仇家枪杀，陈星查得幕后主谋乃香港董姓商人，于是回港准备复仇。同时，香港警方也接到国际刑警的指示，要求介入此案，而负责此案的恰恰就是嘉和。陈星和嘉伦在调查董姓商人时不期而遇，多年后好友重逢，两人都感慨万千。两人现在一个混黑道，一个当警察，兄弟情能否继续？

Po-Chih Leong's debut film was a trendsetter in Hong Kong cinema. Shot from the shoulder, the fast-moving world of cops, informers, drug dealers and other crooks are evoked in a very lively and realistic way. The action all takes place in carefully selected locations, among them the walled city of Kowloon and Yuen Long. The film looks like a documentary and evokes the kind of excitement usually seen in news programmes. The story focuses on the battle between two gangs and starts in Amsterdam, where one of the gang leaders is murdered.