1930s. Hebron. An isolated hamlet in the Deep South of America. The oppressive heat, the constant noise of cicadas, and the stench from the wetlands cause emotions to bubble to the surface.

Dr Alan arrives in town expecting to be the only doctor, but the townsfolk are already under the care of Mama, the local traditional healer.

Pastor Judd shares Dr Alan’s view that Mama’s herbalism has no place in Hebron. Yet his wife, Sarah, longing to become pregnant, secretly uses Mama’s mute adopted daughter, Hope, as a go-between to obtain herbal preparations.

After receiving a potion from Mama, one of the townsfolk dies. Yet, faith in Mama remains unfaltering. Hannah, an expectant mother, chooses Mama’s care over Dr Alan’s.
Pastor Jud is under pressure from his younger wife, Sarah, to have a baby. His expectations of fatherhood and his secret obsession with Hope drive him to publicly denounce Hope as a devil.

Dr Alan is caught between his absolute faith in science and disregarding traditional medicine. Captured by Hope’s innocence and beauty, he decides he should use traditional medicine to cure her muteness.

Dr Alan clashes with Mama over Hannah’s prenatal care. Hannah dies in childbirth, making a choice to save her baby over her own life. Dr Alan uses the tragedy to undermine the town's trust in Mama's abilities as a healer. Shortly after the birth, the baby disappears, and the town is rallied to search for it.

Hope is found with the baby, and later incarcerated. Dr Alan, Judd and Sarah collude to obstruct an official investigation. Sarah bargains to keep the baby as her own.
Hope is finally declared innocent, but it is too late. Mama’s house burns down, and she and Hope leave Hebron.