Sergeant Tong is wracked with guilt after he unwittingly kills a young girl whilst capuring a criminal named Cheung. When the girl's sister is later kidnapped in a ploy to get Cheung released, Sergeant Tong vows to find and rescue her before she comes to harm.

When the Ronin Gang robs an armored car, three cops — Chan, Fong and Wai — go on the warpath. Each has a personal interest in bringing down Ronin leader Tien: he killed Chan's fiancée, humiliated Fong and kidnapped Wai's brother.

Agent Jon contemplates leaving the force until he learns his brother is working as a mercenary for a former colleague who betrayed their team.

Sent into a drunken tailspin when his entire unit is killed by a gang of thrill-seeking punks, disgraced Hong Kong police inspector Wing needs help from his new rookie partner, with a troubled past of his own, to climb out of the bottle and track down the gang and its ruthless leader.

警校同届毕业生张伟杰（谢霆锋 饰）和倪峰（陈冠希 饰）毕业后各在不同的部门当差。杰和峰都在一次行动中的出色表现被派到张铁民（任达华 饰）带领的重案组，致力铲除巴闭巴辣兄弟。张铁民正是张伟杰的生父，杰一直认为生父抛弃了他与母亲，内心充满仇恨。
峰发现了自己母亲的男友肥七（林雪 饰）被巴闭抓住了，峰极力解救却被偷拍了见面的过程。后来巴闭被抓，他以这张偷牌光碟威胁峰放走自己。这时峰已与杰的表妹颖芝（钟欣桐 饰）结婚了，为了家庭，峰不得不对巴闭言听计从，峰被停职。