The novel is in the form of a long letter, or series of letters and vignettes, from the Reverend John Ames to his son (unnamed). He is very old and is dying of heart issues, so this letter is his way of imparting family history, working through thoughts about religion, providing advice, and narrating the events of his latter days. It is not necessarily chronological, as his memories about his father and grandfather are scattered throughout his narration of the present-day events.
Ames grew up the son of a Congregationalist preacher, who was also the son of a preacher. His grandfather was an ardent and eccentric abolitionist who was involved in the violence in Kansas and aided John Brown. He preached his church into war and could never shake his restless, angry spirit. He was a chaplain in the war, lost his right eye, and eventually left his family in his older years and moved back to Kansas from Gilead, Iowa, where they had settled. Ames’s father did not get along too well with his own father, being a pacifist and wary of violence. Ames became a preacher as well. He married a young woman he’d known since childhood, Louisa, but she and their daughter died in childbirth. Ames also struggles with his admiration and sadness for his older brother Edward, an atheist.
Ames cultivated his church in Gilead and lived there his whole life. His closest friend was Boughton, another preacher. Ames was also a little envious of his friend’s large and seemingly happy family, not having one of his own.
Eventually, though, when he was preaching one Sunday in his early seventies, a young woman named Lila, who had a very serious and sad demeanor, came in. He was instantly attracted to her but behaved in the most decorous fashion. She fell in love with him as well and suggested he marry her. They did, and had their young son. Lila and his son provide a sense of immense happiness, delight, and fulfillment for Ames. He acutely feels time passing and is sorrowful that he will not get to see his son grow up.
Ames is living out his last years in relative peace, marveling at the beauty of his life. Unfortunately, Boughton’s son, Jack (named “John Ames” after Ames himself), is returning to be with his own old and languishing father after leaving Gilead in disgrace many years earlier. Ames had always had issues with Jack, who was a mischievous albeit lonely child, who caused trouble as a child and a young man and brought his family, who still loved him intensely, a great deal of disgrace.
Jack returns and Ames finds it difficult to be cordial to him, though Boughton and his daughter Glory, who lives with her father after a failed marriage, are thrilled to have this prodigal son back.
Ames tells his son what Jack had done when he was a young man: he impregnated a poor young woman and abandoned her. The young woman’s family would accept no help, and the child died after a few years of an infection. Ames is worried that Jack, whom his wife and son seem to like a great deal, is a threat to his family.
Jack seeks Ames out to talk, but their encounters are awkward. Ames vacillates between being irritated and piqued by Jack and feeling pity for the man, who is beset by weariness and sorrow.
Eventually Jack tells Ames what is really going on with him, which is that he has a wife and child. His wife is African American, which means that he cannot live with her in certain states, and her family is opposed to him. He has difficulty providing for them but is doing his best. He wonders whether he and his family could live in Gilead, but Ames cannot promise that things would be better here. This news helps Ames understand and care for Jack better, whom he grows to see as a sort of son.
Jack announces that he will be leaving, as he has had a letter from his family. This upsets Boughton and Glory because Boughton is dying and they want the whole family together, but Ames understands that Jack cannot tell his father the truth about his situation and that he does not want to be surrounded by all of the rest of the sons and daughters and grandchildren. Jack departs with Ames’s blessing.
Ames continues to write his letter for his son. In the letter, he is grateful for the beauty of the world; however, he says, he must sleep and pray now.