督察吴落茜(杨紫琼 饰)身手敏捷、嫉恶如仇,某日在赴约时惊见身为伦敦方面调查员的好友身死,原来该调查员因掌握了田氏集团假合约的胶片而被杀。当日,胶片被闯入宾馆的小偷散利痛(孟海 饰)、止立消(岑建勋 饰)无意中盗走,二人将带有胶片的护照交与师兄弟脱苦海(徐克 饰)加工贩卖。同时,伦敦方面派出女警麦瑞(罗芙洛 饰)赴港调查调查员遇害一案。脱苦海师兄弟三人为了摆脱自己调查员遇害一案的嫌疑,选择向警方告密,结果被假护照买家寻仇。而一直在暗中计划夺回胶片的田氏集团,亦派出杀手追踪脱苦海师兄弟的下落,吴落茜与麦瑞的女警组合只得与脱苦海等人以及田氏集团斗智斗勇……Asprin (Mang Hoi) and Strepsil (John Shum), two petty thieves who inadvertently become involved in a murder case when they steal items belonging to a murdered man. The man had hidden an important microfilm in his passport, which the thieves pass onto a forger friend Panadol (Tsui Hark). Inspector Ng (Michelle Yeoh) is assigned to the case, along with Inspector Morris (Cynthia Rothrock) from Scotland Yard. The investigation leads the cops to the bumbling crooks and soon they are on Triad leader Tin's (James Tien) tail, he will stop at nothing to get the incriminating film back and with his hitman and bodyguard (Dick Wei) at his side, he proves too much for the inspectors to catch using legal means, in frustration they give up their badges and go after Tin alone.