But reality never intrudes on James McTeigue's action flick, a hoot for fans of the new globalized martial-arts genre and a movie that's ultimately no more harrowing than its iPhone video game app. Director McTeigue (V for Vendetta) even mocks his own appetite for blood, cutting from one gory scene to a squirt of ketchup.

Most of Ninja Assassin is set in Germany, for no apparent reason other than somebody's desire to use David Bowie's Berlin-era anthem "Heroes" on the soundtrack. The filmmakers — who include co-producers Andy and Larry Wachowski — are mostly American, while the cast comes from all over.

Our hero is Raizo, played by long-haired Korean pop star Rain, who also appeared in the Wachowskis' disastrous Speed Racer. He's being tracked by Mika Coretti (Naomie Harris), a "Europol" agent who is convinced that the long-rumored ninjas are real. She's right about that, but wrong to fear Raizo. He turns out to be an anti-ninja, fighting against the Clan of Black Sand, which adopted, raised and trained him.

A series of flashbacks show how Raizo, a gifted student, came to break with the killers, led by the icy, sadistic Lord Ozunu (Sho Kosugi). The movie's depiction of ninja training is, of course, fictitious. Aside from its murderousness, though, the ninja academy does bear a certain resemblance to the real-life Beijing Opera school attended by such performers as Jackie Chan.

As an apprentice ninja, Raizo couldn't protect his girlfriend from Ozunu's brutality. This being an action movie, he gets a second chance to save a damsel in distress when the Black Sandies decide that Mika is getting too close to the truth.

A series of dimly lighted, sonically dense battles with Ozunu's top killer, Takeshi (Rick Yune), eventually leads to a country that could be Japan, but looks more like a studio back lot. The final showdown is filmed in part from behind a screen, which is soon splattered with red. Such discretion comes and goes, as does the movie's wit; the occasional joke, like one Europol agent's crack that Raizo "looks like he belongs in a boy band," jostles with B-movie hokum about people whose hearts are "special."

If this film had a heart, it certainly wouldn't be special. But as a bloody-minded alternative to sentimental holiday fare, Ninja Assassin shows a welcome bit of edge.