As Isaac grows older, he becomes an expert hunter and woodsman, and continues going with the hunting parties every year. The group becomes increasingly preoccupied with hunting Old Ben, a monstrous, almost immortal bear that wreaks havoc throughout the forest. Old Ben's foot was maimed in a trap, and he seems impervious to bullets. Isaac learns to track Old Ben, but it is useless to hunt him because all the hounds are afraid of him. Sam Fathers, who teaches Isaac Old Ben's ways, says that it will take an extraordinary dog to bring Old Ben down.
Isaac sees Old Ben several times. Once, they send a tiny fyce-dog with no sense of danger after him, and Isaac even has a shot at the huge bear. But instead of taking it, he runs after the fyce and dives to save him from the bear. He looks up at Old Ben looming over him and remembers the image from his dreams about the bear.
At last they find the dog capable of bringing Old Ben to bay: Lion, a huge, wild Airedale mix with extraordinary courage and savagery. Sam makes Lion semi-tame by starving him until he will allow himself to be touched; soon, Boon Hogganbeck has devoted himself to Lion and even shares a bed with him. Using Lion, they nearly catch Old Ben, but Boon Hogganbeck misses five point-blank shots. General Compson hits the bear and draws blood, but Old Ben escapes into the forest. Isaac and Boon go into Memphis to buy whisky for the men, and the next day, they go after the bear again. General Compson declares that he wants Isaac to ride Kate, the only mule who is not afraid of wild animals and, therefore, the best chance any of the men have to get close enough to the bear to kill him.
In the deep woods, near the river, Lion leaps at Old Ben and takes hold of his throat. Old Ben seizes Lion and begins shredding his stomach with his claws. Boon Hogganbeck draws his knife and throws himself on top of the bear, slitting his throat. Old Ben dies, and a few days later, Lion dies as well. Sam Fathers collapses after the fight and dies not long after Lion. Lion and Sam are buried in the same clearing.
Isaac returns to the farm near Jefferson, to the old McCaslin plantation. Time passes; eventually he is 21, and it is time for him to assume control of the plantation, which is his by inheritance. But he renounces it in favor of his cousin McCaslin Edmonds, who is practically his father. Isaac has a long argument with McCaslin in which he declares his belief that the land cannot be owned, that the curse of God's Earth is man's attempt to own the land, and that that curse has led to slavery and the destruction of the South. McCaslin tries to argue with him, but Isaac remembers looking through the old ledger books of Uncle Buck and Uncle Buddy and piecing together the story of the plantations slaves, and he refuses the inheritance. (One of Isaac's inferences is particularly appalling: Tomey, the slave who Carothers McCaslin took as a lover and the mother of Turl, may also have been Carothers McCaslin's daughter by another slave, Eunice. Eunice committed suicide shortly before Turl's birth, and from this and other factors, Isaac deducts that she must also have been Carothers McCaslin's lover.)
So, Isaac refuses the inheritance, moves to town, and becomes a carpenter, eschewing material possessions. He marries a woman who urges him to take back the plantation, but he refuses even when she tries to convince him sexually. He administers the money left to the children of Tomey's Turl and Tennie, even traveling to Arkansas to give a thousand dollars to Sophonsiba, Lucas's sister, who moved their with a scholarly negro farmer who never seems to farm. He continues to hunt and to spend all the time he can in the woods.