A Serbian Film
Carries a reputation of being the eldritch abomination of violent movies. I seeked it for its promise to be most affecting hyperrealistic portrayal of wide-scale agony, in my continuing interest in attaining a firmer understanding of such matters.
It's construction is devious, cinematography so unrelentingly gripping that you will be pulled in, whether you like it or not. Watch it alone uninterrupted and you will feel burning agitation, and numb uncertainty continuing hours on end after the movie.
There are vague societal allusions, but the main focus is on more fundamental psychology of violence.