Plot

Set deep in the wilds of Appalachia, where believers handle death-dealing snakes to prove themselves before God, a pastor's daughter holds a secret that threatens to tear apart her community.

Deep in Appalachia, Pastor Lemuel Childs (Walton Goggins) presides over an isolated community of serpent handlers, an obscure sect of Pentecostals who willingly take up venomous snakes to prove themselves before God. As his devoted daughter Mara (Alice Englert) prepares for her wedding day under the watchful eye of Hope Slaughter (Olivia Colman), a dangerous secret is unearthed and she is forced to confront the deadly tradition of her father's church.

Mara Childs (Alice Englert) is a Pentecostal pastor's daughter raised in a remote community in Appalachia. To her father's pleasure, she is being seriously courted by one of his parishioners, Garret (Lewis Pullman). However, unknown to everyone, Mara is pregnant by Augie (Thomas Mann) who has abandoned the church.

Under pressure from her community and her father, Mara decides to accept Garret's proposal.

Mara's father Lemuel (Walton Goggins) runs a specific sect which incorporates snake handling into his preaching. After a minor dies while handling snakes, Lemuel is warned that the police are investigating him. He allows Garret to claim the snakes are his and lose his job in order to protect his congregation.

Before marriage, Mara's virginity is checked by Hope Slaughter, Augie's mother. Hope realizes that not only is Mara not a virgin, she is pregnant. Hope decides to keep Mara's pregnancy a secret from Lemuel and Garret, but informs Augie and urges him to repent.

In an attempt to reunite with Mara, Augie attends church and pretends to have a spiritual awakening. Lemuel then urges him to handle a snake which proceeds to bite him. Augie begs to be allowed to go to a hospital but is denied by Lemuel and his own family. After he attempts to save himself by cutting the poison out of his arm, he and Mara have a moment together. They are found lying together by Garret who warns Mara to never see Augie again.

The following day Augie is alive, but worse. After hearing the news, Mara informs her friend, Dilly, that she is pregnant with Augie's child. Dilly then informs Garret who attempts to rape Mara. He is stopped by Lemuel, but before Lemuel throws him out Garret informs Lemuel of Mara's pregnancy.

To cleanse Mara, Lemuel takes Mara to church and has her handle a snake. At the same time, Augie's parents, aware that he is close to death, decide to perform an amputation at home. Mara survives her encounter with the snake, but despite earning her father's approval she decides to leave him to help Augie who is still sick after the amputation. With his parents' permission, Mara leaves with Augie to take him to a doctor, promising them that she will always be there for him.