Early in the poorly named, brilliantly executed Hong Kong cop thriller Infernal Affairs, the fiancée of high-ranking police officer Andy Lau talks excitedly about her next novel, the story of a man with 28 personalities; she sees potential in a character who doesn't know who he'll be when he wakes up in the morning. Having lived that way for a decade, Lau takes less delight in the idea: Though his sanity remains intact, his loyalties have been divided since he enrolled in the police academy 10 years earlier at the prompting of his true boss, merciless gangster Eric Tsang. But in spite of his police-force double agent, Tsang still has his share of problems, most of which are caused by a police mole in his own organization: undercover cop Tony Leung. Like Lau, Leung has been on the job for a decade. Also like Lau, Leung fears his luck may soon run out.
A blockbuster in Asia, where it's already prompted two sequels, Infernal Affairs packs in some of the visceral excitement expected from Hong Kong action films, but it keeps most of its thrills above the neckline. As with David Mamet's more populist efforts, the first season of Alias, or Ed Brubaker's great Sleeper comic-book series, the excitement comes less from who's shooting whom than from the knots of deception and play-acting required from undercover work, and the psychic toll they exact on those who undertake them. First seen as a fresh-faced recruit, Leung spends most of the movie looking like hell, in part because the job requires it, but mostly because he feels like hell. Having spent so much time on the side of the angels, however, Lau feels tormented by his persistent tug of his conscience.
Co-directors Andrew Lau (no relation to his star) and Alan Mak anchor the film with tense sequences in which the players confront one another without knowing where their allegiances lie, using Morse code, cell phones, and suspicious gazes as often as they do guns. Creating tension with paranoid editing and an atmosphere of cold urban dread (and in one memorable moment, a saccharine bit of Hong Kong pop), Lau and Mak ratchet up the tension while keeping their viewers as in the dark about where the story is heading as their characters are. They open and close the film with a Buddhist quote about eternal suffering, and when their story can't quite bear its philosophical burden, their protagonists shoulder it for them. Brooding in the midst of a city in which no one truly knows them, Lau and Leung look like men who fear they no longer know themselves.