Marco Mak's 2001 gangland thriller starts off on familiar ground but twists and turns into unexpected developments, as a Hong Kong police inspector goes undercover, wins the confidence of a top gang lord, and becomes richer and more powerful than he could ever be as a cop. Mak, an editor turned director, gives the film a moody look that underscores the paranoia and moral confusion; the ruthless killings endemic to the genre are deftly choreographed, but much of the film's suspense comes from the personal choices facing Daniel Wu as the protagonist and Erik Tsang as the pudgy, jovial gang lord, a scrupulous devotee of the Mafia code of honor. In Cantonese with subtitles. 104 min. Gene Siskel Film Center, 164 N. State, Saturday, March 2, 3:30, and Monday, March 4, 8:00, 312-846-2800.