Tarwater is a 14-year-old boy who lives with his great uncle Mason in the Tennessee backcountry on a plot of land known as Powderhead. One morning in 1952, Tarwater—who insists on being referred to by his last name—watches as Mason dies of an apparent heart attack at the breakfast table at the age of 84. As Tarwater digs a grave for his great uncle, a series of ruminations and flashbacks reveals the family history of the Tarwater clan.

For much of his adult life, Mason suffers symptoms of mental illness, manifested primarily through delusions of religious grandeur. Believing himself to be a Christian prophet acting on direct orders from God, Mason ceaselessly harasses his unnamed sister—Tarwater’s grandmother—over her secular way of life. At one point, the harassment becomes so severe that the sister has Mason committed in a psychiatric hospital. Upon his release four years later, Mason kidnaps his sister’s seven-year-old son Rayber for the purpose of baptizing the child and grooming him to take up the old man’s mantle as a prophet. Although Rayber is only with Mason for four days, the experience leaves a profound impression on the boy. Rayber is deeply committed to his uncle’s religious beliefs until the age of 14 when he bitterly casts them aside in favor of rationality and intellectualism.