Chan Kwok-chung, a Hong Kong/Chinese police inspector, has dedicated his career to putting Wong Po, a notorious triad boss, behind bars. While escorting a witness with damning evidence of Wong's wrongdoings to court, Chan's car is rammed at high speed by another car driven by Jack, a ruthless assassin hired by Wong. The impact severely injures the witness and his wife, whom Jack proceeds to kill after getting down from his car. The witness' young daughter, however, is spared. Chan survives too, but has a piece of glass stuck in the back of his head. When the glass is removed, the doctor notices a tumour in Chan's brain and informs him that he does not have long to live. Chan becomes even more determined to bring down Wong Po, using any means necessary. Three years later, Ma Kwan, a police officer from another precinct, is assigned to replace Chan, who is going to retire soon, and take over leadership of Chan's team, composed of Wah, Sum and Lok. All the three men are very protective of Chan, who has since adopted the slain witness' daughter.