In the farm fields that flank the Sangamon River in rural Illinois, along the same banks where Abraham Lincoln once walked at midnight, another night walker, Dr. John Blair, wrestles with the demons of his past and the divisions in his present. Crossing the harvested fields with his grandson in the long autumn nights, Blair shares his insights into the sectarian and cultural struggles shredding his bucolic township, and forever shapes the young mind of Jack Blair.

The landscape-with its cluster of local farms, small belts of forest, and its fished-out hamlet-becomes a moral arena in which grandfather and grandson confront the problems stirring between two deeply rooted American traditions: individual conscience versus the "come ye out and be separate" mandate of a local messianic cult. Locked in a struggle for the hearts and minds of America's plain people, the once-beloved country doctor becomes a leading figure in bringing about a brutal but ultimately healing catharsis, and emerges as Emerson's ideal sage: "a man whose wisdom flowers like corn growing in the night."