A sterling ensemble cast turns this modest indie into something worth savoring.

In the disturbing drama, “Them That Follow,” Walton Goggins plays Lemuel, a preacher who uses snakes as a pivotal part of his worship service.

An isolated community has formed around Lemuel’s church, as a close nit group partakes willingly in Lemuel’s antics, which occasionally conclude with someone dying from poisonous snake bites. While the local law enforcement is keeping a close watch on the church, internal struggles take place.

Lemuel’s daughter Mara (Alice Englert) is pregnant and keeping it a secret. Mara is still being courted and there are mounting pressures from church members to settle down with a nice young man.

Set in Virginia (a reference is made to Leesburg) but filmed in Ohio, “Them That Follow” marks the directorial debut of Britt Poulton and Dan Madison Savage, helming a screenplay they co-wrote. Their film creates a feeling of unease that never lets up and succeeds as a dramatic work.

The film maintains its grip through the work of a terrific cast.

Recent Oscar winner Olivia Colman gives an especially intense performance as a devout church member. Colman’s accent slips through a few times, but the forcefulness of her presence is undeniable. This is entirely removed from her prior work as Queen Anne in “The Favourite.”

Kaitlyn Dever, so great in this summer’s “Booksmart,” is affecting as Mara’s best friend and Goggins, to his credit, plays Lemuel’s religious fervor in a practical manner. He never resorts to playing the character as an all-out madman.

Comedian Jim Gaffigan is surprisingly good in a supporting role. His presence is initially a distraction, but he grows nicely into the part; his participation and endorsement in an indie drama like this is a nice surprise.

The film is carried overall by Englert, who lets us see the aching heart underneath the dutiful, long suffering daughter who is conflicted but fully devoted to her father.

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The strength of the performances create the infrastructure of this hermetically sealed world. While “Them That Follow” is effective in the moment, it’s limited on a deeper level. Some of the larger questions (like, how much of a case does the law have against the church?) go unanswered and, aside from the core cast, this feels under-populated.

The screenplay goes into soap opera melodrama at the mid-point and it’s pretty clear where all of this going. You can’t have a movie with poisonous snakes and not have a big scene with an ultimate test of faith.

As a commentary on a religious group with a domineering patriarch and old fashioned sexism practiced, this feels late to the conversation. There are some shockingly violent, outrageous developments in the final stretch.

Yet, any recent episode of “The Handmaid’s Tale” and director Mary Herron’s little-seen but remarkable “Charlie Says” (portraying the story of the Manson family from a female perspective) are much stronger.

In a way, so is Quentin Tarantino’s “Once Upon a Time…In Hollywood,” in which a subplot with the Manson followers becomes a central part of the film’s climax: while Tarantino is mocking the Manson family (a refreshing choice, after years of films using them for exploitation and cheap thrills), he is still portraying the powerful control Manson had over his followers.

That scary dynamic is absent here.

While Lemuel is hardly a Manson type, the dogma of his church, the psychological pull of his persona and how he maintains a flock, in spite of his box of snakes, is never made clear.

At one point, Lemuel declares, “Woman is the first sinner, and she must be cleansed.” Writer/directors Poulton and Savage have made a strong statement about a woman’s budding sense of empowerment over her body, as well as her ability to separate the inner workings of her faith from the demands of being a part of a religion.

All of that is commendable, though a love-triangle that takes shape winds up doing very little for the narrative overall. The showdown with a curious, jittery rattle snake shouldn’t seem inevitable but it does.

“Them That Follow” is worth seeing for the strength of its performances and the novelty of its cult-as-community premise. Yet, it seems like it sold itself short by emphasizing its love story over its far scarier look at how to maintain one’s humanity in a nightmarish atmosphere. It really could have used less forbidden romance, more rattle snakes.

Two and a Half Stars