If you've chosen to watch a film titled Ninja Assassin, you have no business complaining it's too violent. This slick slice of martial-arts mayhem stars Korean pop-star Rain as Raizo, an orphan raised from an early age to be a cold-blooded killing machine, and member of a secret army of ninja assassins.

But after his brutal master kills the girl he loves, Raizo turns on his clan with the help of an Interpol agent (played by Naomie Harris), and what follows is approximately 90 minutes of slow-motion acrobatics and buckets and buckets of blood-spill.

Kicking off with an explosive opening scene in which a gang of Asian punks get their just-deserts at the hands of invisible executioners who spray them with a volley of lethal sharp objects, Ninja Assassin hits the ground running and seldom lets the pace drop. However, a plot this thin needs charismatic actors to lend dramatic weight to the film, and here is where this one fails.

Leading man Rain competently delivers what's required of him in the action scenes, lending grace to his chop-socky moves, including a stunning sequence in which he practices handstands on a bed of spikes. But when expected to charm with his expressions and dialogues, he grapples.