The roaring popular success of Peter Chan's Wu xia in China - renamed Dragon for export - is no mystery: It's an adept genre exercise with rare primal depths.

When a mild-mannered peasant unsheathes the powers he has long kept hidden, the results can be spectacular. The same can be said for Peter Chan Ho-sun's Dragon, a martial-arts morality play as lithe as it is forceful.

It's never dull though, and the familiar characters and stock motivations are convincingly put across. And there's always Xu, who's turned to acupuncture to suppress his empathy, as you wait for the inevitable moment when suppressing it won't be enough.

Dragon is partly an homage to "One Armed Swordsman," a 1967 kung fu classic whose star, Jimmy Wang Yu, plays the new movie's arch-villain. But there's much Western influence: Jinxi's plight recalls David Cronenberg's "A History of Violence," and Baijiu's cerebral and flashy style of detection - complete with animated glimpses of victims' innards - suggests Guy Ritchie's Sherlock Holmes series. Dragon is also one of several recent Chinese crime movies that borrow from CSI-style TV dramas.

Dragon has enough interesting left turns in style, mood and psychodrama to make it stand out.