Your appreciation of this Australian horror movie—based on a series of gruesome murders that took place in an Adelaide suburb in the 1990s–will depend on whether you think its artistry justifies its unrelenting ugliness. It’s quite accomplished in a formal sense, engendering a trancelike fascination mainly through atmosphere (though it doesn’t shy away from gore either). First-time director Justin Kurzel gets effective, natural performances from professional and nonprofessional actors alike; the movie is nauseating partly because it feels so intimate. Kurzel and screenwriter Shaun Grant want to understand their characters, blue-collar vigilantes whose group is taken over by a charismatic psychopath, but that doesn’t make the story any easier to watch.