Like his shanty boat, John had grown old on the river, the Big Sandy in eastern Kentucky. The river was his friend, and he loved it. Tied to the willows along the river bank, the shanty boat was his home. Every May along with the rains, came the giant catfish Scrapiron Jack, out of the Big Ohio and into the Sandy to feed. To some of the townspeople, this great fish, hooked many times and escaping as many, was a figment of old John's imagination. But he was real, and each succeeding spring the challenge between the two was renewed.
The small boys of the town loved to visit the shanty boat and to hear John's stories; but there was a tragic accident, and the boys did not come again. Alone with Limpy, the crippled duck, John awaited the return of summer when he would again match his wits against the fish that had made fools of all the rivermen. When they finally meet in the last decisive battle, old John has to make the biggest decision of his life.