In 1956, toward the end of Reverend John Ames's life, he begins a letter to his young son, a kind of last testament to his remarkable forebears. Ames is the son of an Iowan preacher and the grandson of a minister who, as a young man in Maine, saw a vision of Christ bound in chains and came west to Kansas to fight for abolition: he "preached men into the Civil War".
Ames is troubled, too, by his prodigal namesake, Jack (John Ames) Boughton, his best friend's ne'er-do-well son, who seems to be a living contradiction of everything that Ames stands for. When Jack returns to Gilead, his hometown, he and Ames attempt haltingly to reconcile, and as they do, long-hold secrets that carry fatal consequences come to light.