Original Danish title "Retfærdighedens Ryttere."
Mads Mikkelsen is Markus Hansen, who returns home from Afghanistan after the death of his wife in a train accident. We quickly find out that Markus doesn't have much of a connection with his daughter, and he's a bit violent. Soon, Otto (who was on the train, played by Nikolaj Lie Kaas) and a couple of his friends approach Markus, telling him that her death wasn't an accident, but a targeted assassination of a witness in a gang court case sitting near her on the train. They were unable to convince the police of this though. This leads them to the gang "Riders of Justice," and a very darkly comedic tale of revenge.
Imagine a stock American revenge flick - pick one that's got some comedy in it. Now, mentally throw it in a blender with the most twisted Nordic comedy you've ever seen - I'm thinking of "O'Horten," but nobody sane has seen that. Anyway, what would come out of the blender would be this. It's closest living relatives are "A Somewhat Gentle Man" and "In Order of Disappearance" ... although I'd argue this is at least a bit better than either of those.
Markus is a supremely capable military man. This is a classic element from the American revenge flick. But he's really not good with the emotions - his, his daughter's, or anyone else's. The fact that this gets discussed is not something you generally see in the American revenge flick. He accidentally builds himself a new family from a variety of very damaged individuals. This is an element from comedies the world over. The resulting movie is wildly perverse and often quite funny.