Just to make sure that we know what we’re getting in Ninja Assassin, the film’s first sequence wastes no time telling us. A gang boss is getting a tattoo when a letter arrives. It is sealed with wax and when he breaks the seal and opens the letter, out pours some black sand. The tattoo artist goes pale – he’s seen this before. Even as the boss and his gang laugh at the old man’s fears, they are suddenly sliced to ribbons in one of the goriest action scenes I’ve ever seen.