The Hong Kong crime thriller Infernal Affairs begins with a Buddhist epigram, though not a particularly memorable one (something about "Continuous Hell" being the worst of the eight hells). Perhaps more important than the passage itself are the echoes it raises of Jean-Pierre Melville's seminal 1970 policier Le Cercle Rouge, which also opened with a Buddhist citation (though in this case one made up by Melville himself): "When men, even unknowingly, are to meet one day, whatever may befall each, whatever their diverging paths, they will inevitably come together in the red circle."
Despite its atrocious title--it sounds like a sequel to The Devil in Miss Jones--Infernal Affairs is a worthy descendent of Melville's cinema of criminal cool and a film equally suited to his invented quote. Its men of diverging paths are a cop who has spent years posing as a gangster and a gangster who has spent years posing as a cop. The "red circle" where the two will ultimately meet to have their fates decided is a sun-bleached roof looming over downtown Hong Kong.
It's a long road to that rooftop rendezvous, however. The movie opens with its two protagonists still in their teens. Lau, the young recruit of a drug kingpin named Sam, is assigned to join the police force and work his way up through the ranks as a mole. At the academy, his path briefly crosses that of Yan, a promising cadet who is apparently expelled for breaking the rules. In fact, Yan's dismissal is merely a cover story: He, too, is beginning a career as a mole, infiltrating Hong Kong's gangs on behalf of the police. Fast-forward ten years to the present day. Lau (now played by Andy Lau) is a young hotshot detective working under police superintendent Wong, though still secretly reporting to drug lord Sam; Yan (Tony Leung), now one Sam's deputies, is informing on him to superintendent Wong.
The event that launches the film's dramatic arc is an attempted drug bust, presented as a terse game of cat and mouse between Sam and Wong, with each relying on his man in the other camp to keep him a step ahead. The outcome is essentially a draw: Thanks to a morse-code-tapped message from Yan, the cops are able to break up the drug deal, but Lau warns Sam by wireless email in time to destroy the evidence. As a consequence, each side now recognizes there is a mole in its midst, but neither knows who it is. The situation plays out like a brilliant, funhouse variation on the Kevin Costner thriller No Way Out: Superintendent Wong assigns Lau the task of finding the department mole (i.e., himself), while also telling Yan to see what he can learn from inside Sam's gang; Sam asks the same of Yan, his presumed underling, and Lau, his secret operative.
It's an ingenious construct, and if the perfection of its symmetry sounds forced, it doesn't play that way onscreen. Co-directors Alan Mak and Andrew Lau (who also served as co-cinematographer and producer, but is not related to star Andy Lau) present the story straightforwardly, with a minimum of self-congratulation for the cleverness of its premise. The visual style of the film, with its gleaming urban blues and silvers, owes much to Michael Mann, but here too the filmmakers decline to show off: Though frequently striking, the camerawork is also brisk and unwallowing. Thanks to the heady pace--and the constant danger that one or the other protagonist will be found out--Infernal Affairs has the feel of an action movie without resorting to the tiresome obligations of car chases and exploding buildings. In contrast to the John Woo-style mayhem that prevails in so many Hong Kong releases, there's no violence at all until the one-hour mark. On a few occasions, the movie slips into a stereotypical sentimentalism, but these digressions (chiefly a subplot involving Yan and his pretty psychiatrist) are mercifully brief. For the most part, Infernal Affairs is an object lesson in narrative economy. Though Mak and Lau are meticulous in setting up the movie's myriad twists and developments, they don't waste a lot of time walking viewers through them. (When Yan runs into a former girlfriend, for example, the filmmakers hint both that she left him because she thought he was really a gangster and that he is the father of her young child, but they never spell out either point explicitly.) Infernal Affairs is the increasingly rare entertainment that expects its audience to do a little bit of work themselves, and it is all the more engaging for it.