Photo: Tony Leung as Yan and Andy Lau as Lau in Wai Keung Lau and Siu Fai Mak's Infernal Affairs

You probably already know the extent to which Asian cinema has influenced the work of Quentin Tarantino. Proving that the exchange of pop cultural parts works both ways, Wai Keung Lau and Siu Fai Mak's successful Infernal Affairs trilogy could be the incestuous syllabus for "The Effects of The Godfather, Michael Mann, Tony Scott, and the American Police Procedural on Asian Cinema." That an American remake is already in the works (with Matt Damon, Leonardo DiCaprio, and Martin Scorsese all in on the action) is beyond ridiculous. Lau (Andy Lau) and Yan (Tony Leung) attended the same cadet academy, the former sent there by a drug kingpin, Sam (Eric Tsang), who prefers to cultivate his contacts at the police station. Many years later, both men are working as moles—Lau as a gangster infiltrating police headquarters and Yan as a police officer with a mainline into the triad underground. Naturally, the longer each man works for the other side, the blurrier the lines between good and evil become.   Ed Gonzalez