"Miu gaan diy" is a tale told amongst the backdrop of the never-ending was between the police and the Triads of Hong Kong. Placed undercover long ago and almost forgotten, Chan Wing Yan (Tony Leung) has been able to rise up along the ranks of the Triads and gain a foothold of power. Meanwhile the Triads have done the same exact maneuver and Inspector Lau Kin Ming (Andy Lau) is there inside man who has been in the police force for so long he’s gained a position of command. As they inform to their own sides of the moves of the other, both Chan and Lau begin to feel the stress of a double life. Over time they become torn between their loyalty to their superiors and the camaraderie they have earned with their supposed organizations they have each infiltrated. Now both Chan and Lau have to get out of this alive as each side becomes ever more aware of an inside mole.