Jack Boughton confesses to John Ames the reason he's home: he can't provide for his wife and child, a family he has not told his father or siblings about. Jack's habits, including alcoholism, prevent him from being the husband and father he'd like to be. Whether the little guidance Ames gives him will prove beneficial remains unknown. The prodigal son leaves Gilead and his father, returning once again to the world outside. Ames sends him off with a blessing and writes to his son of what he can't tell Jack's family. Ames prays for his own son, hoping he'll be brave and useful.
The ending of the novel is inconclusive: we don't know for sure what will happen to either Jack Boughton or John Ames's son. What's important is that some big lessons about love, life, and family have been learned, and possibilities for the future have been opened up.