Turning the Jonestown massacre into a found-footage horror film sounds in theory like a tasteless bit of exploitation. Yet in the hands of one of contemporary horror’s greatest directors, Ti West, ‘The Sacrament’ plays as a deeply disturbing human drama that can be called a horror movie only out of a lack of any other appropriate genre classification.

Writer/director Ti West has carved a place for himself in the horror genre as a brilliant formalist whose exquisitely constructed and teasingly suspenseful movies ‘House of the Devil‘ and ‘The Innkeepers‘ offer all of the atmosphere and characterization so often lacking in contemporary genre fare. He’s a filmmaker who understands how to use film style and grammar to sneak under his audience’s skin, rather than rely on easy shocks and gore. So it comes as a bit of a surprise that his latest feature abandons his greatest gifts as a filmmaker for the found-footage schtick. At least, it feels that way until you see the movie. In many scenes, ‘The Sacrament’ is West’s most deeply disturbing directorial outing to date, and that’s entirely because he ditches film formalism to let his scares slip out purely through his characters and the unsettling situations they find themselves trapped in.

The movie stars mumblecore and genre specialists AJ Bowen (‘You’re Next’) and Joe Swanberg (‘V/H/S’) as a pair of journalists who travel to a secluded tropical island to film a documentary about a cult dubbed Eden Parish. The sister of one (Amy Seimetz) recently joined up, describing it as a joyous commune that she wants her brother to show off to the world as an alternative lifestyle paradise. However, pretty much as soon as Bowen and Swanberg arrive, things feel wrong. The leader who everyone refers to as Father (Gene Jones) has more to say about self-promotion and self-aggrandizing than anything resembling a genuine humanist philosophy. Rather quickly, residents from his community start begging the filmmakers to help them escape.

If this sounds a lot like Jonestown, West essentially retells the Jim Jones story from the perspective of the journalists who sparked the Kool-Aid tragedy by showing up at the commune right as things turned south, as if their gut-wrenching story somehow never got a feature film treatment before now.

West’s rendition of this story never once feels tasteless because he takes the time to present every character as a lost human and never settles for easy shocks. The most frightening element of the whole movie is undoubtedly Gene Jones’ performance as the cult leader, delivered in calm and measured tones that never mug for evil. It’s all frighteningly believable, and West heightens that reality through his found-footage conceit that is more necessity than gimmick. It draws audiences in to the immediacy of the story and lets the performers and situations dictate the viewers’ emotional response rather than directorial handholding.

The film also feels disturbingly real throughout thanks to impressively naturalistic performances from Jones, Bowen, Swanberg and Seimetz, whose background in indie character-driven movies carry over perfectly. No one on the cast or crew of ‘The Sacrament’ treated the project as horror material in a conventional sense. They created a drama that just happens to be terrifying because it depicts the most infamous and disturbing cult tragedy of the 20th Century.

‘The Sacrament’ may not be West’s finest work, but it’s further proof that he’s a genuinely talented filmmaker who works in the horror genre because he loves it, not just to be a profiteer or sleaze merchant. (Not that there’s anything wrong with top tier sleaze, of course.)