Acclaimed director Johnnie To scores again in this electrifying action thriller starring pop superstar Andy Lau and Japanese idol Takashi Sorimachi. Top assassin "O" (Sorimachi) finds his spot challenged by Tok (Lau), a mysterious man whose flamboyance and reckless styles of his killings made him the latest darling in the world of hitmen, and who vows to become the No.1 killer by challenging "O" into duels. Hot on both men's trails is Interpol Inspector Lee (Simon Yam).