Bumbling Hong Kong detectives Lui (Kenny Bee) and Leung (Tony Leung Ka-Fai) go undercover in an apartment complex to keep watch over Pearl Chan (Carina Lau), a high school teacher who is suspected to be connected to a rare diamond theft involving a notorious thief named Mr. Mickey (Simon Yam). Meanwhile, the legendary Black Rose (Veronica Yip) appears and is also in pursuance of Mr. Mickey, wanting him to surrender himself and the diamond in order to clear her name.

大盗麦基（任达华饰）盗取马拉之星，被神探吕奇（梁家辉饰）及梁醒波（锺镇涛饰）两人拘捕，而马拉之星则下落不明，麦基将罪名嫁祸黑玫瑰（叶玉卿饰）。某夜麦基狱中逃脱，前往找寻旧爱陈宝珠（刘嘉玲饰）取回收藏马拉之星的锁匙，而警方亦命神探吕奇与梁醒波二人捉拿麦基及找回马拉之星。为了捉拿麦基，二人各出奇谋同时黑玫瑰为了洗脱罪名，亦缠上吕奇……

大盜麥基在搶劫的時侯被兩名警察呂奇和梁醒波抓着，但麥基居然把罪名推給黑玫瑰，自己在深夜逃出監獄，警方決定再派呂奇和梁醒波把他抓回來.....