The movie opens with Sam (Eric Tsang), the underground boss, drinking a toast with Police Inspector Ming (Andy Lau) and several other youths that he handpicked to infiltrate the police force. It is a scene filled with both irony and sinister anticipation that is immediately juxtaposed with a scene in which Yan (Tony Leung) appears to be kicked out of the police academy but secretly accepts an assignment to act as a mole in Sam's group.
Years later, Yan has risen through the ranks of the underground gang to become Sam's right-hand man while Ming has mirrored this climb in the police force hierarchy, becoming one of its most promising officers. Indeed, each man is a reflection of what the other would have become had they not chosen their respective paths.
Despite his rapid ascent, Yan begins to question his commitment to the cause as the years pass by without a sign of light at the end of the tunnel. And as the movie progresses, Ming comes across every bit as tormented as Yan. While Yan has the consoling knowledge that moral righteousness is on his side, Ming struggles constantly with his desire to be "one of the good guys." His opportunity will come, but it is the conclusion that lends such a deep poignancy to the story.
The film rapidly develops into suspenseful skulduggery when Yan and Ming are assigned by their respective bosses to root out the moles in their organizations. They are thus inadvertently pitted against each other, both driven by the threat of being found out before managing to destroy the other. In a sense they both succeed. This is where "Infernal Affairs" is so intelligently written; it doesn't try to judge. Rather, it allows one to make sense of the circumstances forcing characters into a wrenching end.
Tony Leung, who carried away Best Actor at Cannes for "In The Mood For Love" (2000), again delivers sublimely in a role seemingly tailor-made for his trademark brooding personas. He adds just the right degree of knowing resignation to a character clinging to the abstract concept of morality, and little else, to sustain himself. Lau, in possibly his finest turn, has the more difficult job of conveying the churning that goes on in Ming's head but acquits himself with ease. There is a sense of finality in the vivid rooftop scene which emphatically shows what these two actors can do with the right direction and script. Supporting them in the cast is veteran Anthony Wong as Yan's uncompromising superior, bringing his usual authority and depth to bear.
"Infernal Affairs" lets itself down, however, by at times being unnecessarily confusing and mysterious. And although the premise is ingenious, the plot relies far too heavily on coincidence for its development. It is to the credit of the directors, however, that this unhealthy reliance on coincidence is barely perceptible in the well-judged pacing. In Hong Kong and China, at least, the film has proved such an unexpected hit that it has generated both a prequel and a sequel that seek to provide more context to the original. And in the U.S., word on the street is that Brad Pitt will star in a Hollywood remake of this film. This subdued thriller challenges the limits of its genre in both Hollywood and Hong Kong, and on occasion transcends them. If you're going to watch one Asian film this year, make it this one.