Treating crime drama like a death cage tournament, this rousing, dark-hearted Korean epic doesn’t know quite when to stop once it begins, which is with an ethnically Korean Chinese cabbie (Ha Jung-woo) traveling to South Korea to find his errant wife and pay off her debt by killing a gangster. Nothing goes according to plan, of course, unleashing a cataract of whackings and wild chases, and setting two rabid crime bosses (Kim Yun-seok and Cho Seong-ha) at each other’s throats, in an undulating blood festival of carving knives, hatchets and ka-thunking soup bones. (It’s a little tough to keep all of the doomed secondary characters straight, knee-deep as they are in henchmen corpses.) Writer-director Na Hong-Jin achieves a vibe of urban desolation right off the bat, and deepens the mayhem with acutely observed and charged details about illegal-immigrant life. If anything, Na’s film is too much of a good thing, exceeding credibility too often (the punching-bag hero is far too lucky—good and bad—and absorbs a hilarious amount of punishment) in its pursuit of despairing violence. But that’s the Korean way, and Na nails down the bottom feeder realism while slouching toward video-game hyperbole.