'The end is bullshit. The means is what you live with.' Thus alcoholic ex-cop Cox to son Wahlberg, engaged in undercover double games in New York's Chinatown. You might think the means is bullshit, too, if the NYPD is setting Irish cops to infiltrate the Triads. 'You're worse than white, you're green,' sneers the head of the Asian Gang Unit, Chow Yun-Fat. Yet the newcomer's enthusiasm wins him over - that and his readiness to get his hands dirty if it gets the job done. This is a satisfying, serious reprise of traditional cop-thriller quandaries about ambivalent father figures, integrity and betrayal, public and private moralities. Director Foley frames it in the restless surveillance style of '70s films like The French Connection and Serpico. On the other hand, the movie is also designed as a star vehicle for Hong Kong action hero Chow, which means that the prevailing naturalism is chained to HK-style eruptions of spectacular gunplay and a death toll in keeping with '90s bloodlust. Affecting a cynicism that's even-handed if hardly progressive, it finds its most compelling culture clash in the John Woo-like play-off between Chow's delicious, extravagant scene-stealing and Wahlberg's fretful, internalised approach. They build up an affection that's only a whisker short of homoerotic.