在这部PTU女警之偶然陷阱动作片中,在香港新型建筑群里，一群穿得高贵华丽的中产人士，及医生、律师、商人等各种专业人士，正在参加一个医学院所办的酒会，当中有皮肤科医生家豪及其工作伙伴玛丽、从日本来的刑警美惠、为捉拿非法商人而卧底的女探员，以及途经的女装PTU警察杨芳芳…… 众人都各怀目的来到这个酒会。 台上正在举行抽奖活动，每人都有一个幸运号码。突然，有四名青年持枪闯入，其中一人还受了伤。会场外，则已被重案组包围。 四名青年中受伤的那个伤重毙命。这令痛失亲弟的青年发了狂，他要用抽奖方式处决人质来为弟弟陪葬。被抽中的是医生家豪，他也是躲在暗处的PTU女警，杨芳芳的丈夫！
In one of the modern buildings in Hong Kong, a group of well dressed middle-class people are attending a party held by a medical college. Among them are Ka Ho, a doctor, and his sexy partner Mary, a crime woman and a booty buyer from Japan, a German killer named Stefan, a sexy undercover cop for catching a lawless merchant. All these people, not knowing each other, met more than once on the morning of that day. A lucky draw is being held on the stage, everybody has a 'lucky number'. Suddenly four unexpected guests come. One of them has received a bullet wound while another is holding a gun. Outside the banquet hall a superintendent of police has arrived and his teams have surrounded the building. Meanwhile, inside the hall, as the injured youngster died, his brother, the other youngster, has turned crazy. In his anger, he decide to kill hostages by drawing numbers....
