Plot

An old man hires the world's number one professional hitman, "The King of Killers", to assassinate a Japanese plutocrat who wiped out his family during the Sino-Japanese War. His remuneration, however, turns out to be a box of military notes.

Prior to his death, the plutocrat set up a billion-dollar revenge fund to reward the one who can slay the instigator and "The King of Killers". The world's top assassins all sign up through their agents, including the plutocrat's grandson and the world's second best hitman GREY WOLF. Among all, one team is not widely known - TAI FENG (starring Jet Li) and his agent SAM WONG (Eric Tsang). TAI is a rare breed of hitman. He is so softhearted that he has never succeeded in killing anyone before.

All the contenders start fighting for clues. When TAI finds the instigator, he feels pity for the sick old man. He even protects him against GREY. During the fight, TAI is shocked to spot SAM covering the old man covertly.

The old man finally dies of illness. TAI questions if SAM is "The King of Killers". SAM not only admits but asks TAI to join him in swindling the fund by killing him in public. Meanwhile, the police discover SAM's real identity and force TAI to betray his agent. While TAI is at the crossroad, SAM's daughter KK (Gigi Leung) comes to invite her father to attend her graduation. SAM refuses, not wanting to keep her any closer.

TAI is touched by KK's sincerity and remains loyal to her father. Together with SAM, they get rid of other killers and are about to launch their plan. At the critical moment, however, KK who has no knowledge of her father's deal suddenly shows up. TAI and SAM begin to argue and suspect each other, leading to a real assault - TAI kills SAM amid an explosion.

SAM is declared dead and the billion dollars go to TAI. A month later, he withdraws the money at a Swiss Bank. Waiting for him there is KK, who is all ready to take revenge for her late father. Yet to her total surprise, SAM is standing next to TAI . . .