Fans of the Hong Kong action/crime movie Infernal Affairs (2002) and its 2003 prequel (both of which served as inspirations for Martin Scorsese's The Departed) seem split over this final part of the trilogy, which picks up at the conclusion of the original film and brings the tortured path of cop and Triad mole Lau Ming (Andy Lau) to a close. The story picks up shortly after the execution of undercover cop Chan Yan (Tony Leung), with Lau now heading up an internal investigation to ferret out other Triad plants working in the police department. While Lau works frantically to eradicate any connection between himself and mobster Hon Sam (Eric Tsang), his actions are being carefully observed by Inspector Yeung (Leon Lai), who bears a personal grudge against the crooked cop. Less aggressively action-oriented than its predecessors (though certainly still featuring plenty of gunplay), Infernal Affairs 3 suffers from a disorienting structure that shuttles back and forth between events in the first and second film (which conveniently allow stars from both pictures to make return appearances), but the central idea--the final descent of Lau--remains engaging. DVD extras are comprised of a making-of featurette and theatrical trailers. -- Paul Gaita