Film preview: 'Them That Follow' 

It requires a confident directorial hand to tell stories about little-understood subcultures with beliefs far outside the comfort zone of the average person. Say you're making a film set in the world of snake-handling churches: It can be tricky to find the right tone for such a tale, where it's already a struggle for most viewers to understand a group of people whose faith leads them to test their devotion by getting handsy with live, venomous reptiles.

There's a fine line between making an attempt to truly understand what drives this behavior, and simply using it as an excuse to gawk in horror. There's a natural instinct to veer toward the exploitation for effect. And while "Them That Follow" -- the moody debut feature from filmmaking team Britt Poulton and Dan Madison Savage -- doesn't always keep to the right side of that line, it remains a compelling story about the clash between spirituality and the messiness of life.

The film centers on a poor, isolated community of evangelical snake handlers deep in the Appalachian Mountains. This particularly sect is led by pastor Lemuel Childs (the always great Walton Goggins). His daughter, Mara (Alice Englert) has been raised in the church, but is facing a crisis as her heart begins to lead her down a path that runs counter to her faith.

Mara is engaged to be married to Garret (Lewis Pullman), a fellow member of the church and a religious true believer. But when we see Mara shoplift a pregnancy test from the local convenience store, we surmise their impending marriage may face some complications.

Especially when we learn of her closeness to her childhood sweetheart Augie (Thomas Mann), who's begun to distance himself from the church and is already on thin ice with the community.

Augie's parents Hope (Olivia Colman) -- who also goes by the name Sister Slaughter -- and Zeke (Jim Gaffigan) struggle to accept that their son has become a nonbeliever. Lemuel, for his part, is quick to blame the work of Satan for any cracks that may develop within his congregation.

We learn that if one does get bit during a service, it's God's way of testing you, and only the power of prayer can heal you. A trip to the hospital is the coward's way out; a sign your faith isn't strong enough to trust that God will spare your life. More practically, it's also a side effect of the church's rules against fraternizing with outsiders and a fear that any interaction might tip off the authorities -- a problem for a church whose practices aren't, strictly speaking, legal.

The plot machinations can verge on melodramatic, but Poulton and Savage's filmmaking maintains a steady hand on the emotion of their plot. At its heart this is a story about how young people raised within a religious group react when they no longer feel they fit in with the doctrine that's been ingrained in them their entire lives. Here, snake-handling functions as a stand-in for any system of radical beliefs we have a hard time wrapping our heads around.

Poulton and Savage's script doesn't demonize its characters; it genuinely trusts in the sincerity of their beliefs. Still, I couldn't help wishing for a bit more insight into why an occasionally headstrong young woman like Mara would adhere to such patriarchal and misogynistic culture. Mara remains a closed off character for much of the film, and it gets frustrating when characters stubbornly refuse to say the things they need to.

The film gets a lot of mileage out of a phenomenal cast, including newly-minted Oscar winner Olivia Colman as the devout Hope, a convert to the faith who affirms that religion has saved her life. And Kaitlyn Dever, fresh off of her winning turn in "Booksmart," plays Mara's lonely best friend Dilly, who's living on her own after being abandoned by her mother.

"Them That Follow" remains a slow burn for most of its running time, only for the last act to ratchet up the tension to near unbearable levels. Much of the film's considerable suspense comes from the realization that it's only a matter of time before one of these characters ends up on the wrong end of a pair of fangs -- call it Chekov's rattler.

Shot by cinematographer Brett Jutkiewicz, the film takes on the brown and yellow tones of the fall foliage of its perpetually gloomy forest setting. The densely wooded surroundings only further emphasizes the claustrophobia of this insular community and its people trapped in often impossible circumstances. As it peers into this unusual subculture, the film ultimately offers a potent look at the ways fanaticism can poison the actions of even inherently decent people.