Now an old man, Isaac McCaslin travels by car with a group of younger men to a hunting camp in the Mississippi River Delta. He thinks about the dwindling of the wilderness, argues with his young relative Carothers Edmonds about America's role in World War II, and listens to Will Legate hint around about Edmonds's love affair with a negro woman who lives near the hunting camp. They travel to the camp by car and motor-boar, then eat dinner and talk. Over dinner, Isaac and Carothers argue about human nature: Isaac says that "most men are a little better than their circumstances give them a chance to be," but Carothers disagrees and says that men behave well solely out of the fear of punishment.
Isaac does not sleep that night; he stays awake, listens to the wilderness, and thinks about the past. Isaac thinks that he and the wilderness have the same life span--that there was just exactly enough wilderness left when he was born for deforestation and development not to have completely annihilated it until he died. The wilderness has dwindled throughout his life.
Early the next morning, as the men leave to hunt, Carothers brings an envelope to Isaac and asks him to give it to the girl who will come to see him. Isaac knows Carothers is attempting to pay off a lover, and he berates him for it, but Carothers leaves. Later, a light-skinned young girl comes to the tent with a child. Isaac is upset, and he's even more so when he realizes that the young girl is a negro. She seems to know who he is and says that she is the granddaughter of Tennie's son James Beauchamp--Tennie's Jim, as he was called, who used to go on the hunting expeditions with Isaac and General Compson and Major de Spain and McCaslin Edmonds.
Immediately after the girl leaves, Legate comes in, looking for a knife. Carothers has killed a deer, and Legate refuses to say whether it is a buck or a doe, which hunters are now forbidden to kill. Isaac knows that the deer is a doe.
The hugely significant event in this story, set again in Isaac's advanced old age, is the reunification of the "black" branch of the McCaslin family tree with the "white" branch. Carothers Edmonds is Carothers McCaslin's great-great-great-grandson and the heir of the white branch; his lover is McCaslin's great-great-granddaughter and the heir of the black branch. Their child stems from both sources and from the single ultimate source, Carothers McCaslin (who is described as self-engendering, despite all biological evidence). Nevertheless, Isaac is upset by the revelation; he believes that history is not yet ready for the union of the branches and of the races. But Faulkner suggests that history marches on despite human opinion of it; the child of Carothers Edmonds and Tennie's Jim's granddaughter will carry the McCaslin family forward into the future.
Around this revelation, the story takes up the question of gender difference--not so much in political terms as in psychological terms and in terms of the regeneration of the species. The symbolism is a bit heavy-handed (the men are no longer allowed to kill does, only bucks; Carothers Edmonds says that history is never lacking in does and children), but it becomes more central to the novel's main concerns when we remember that Carothers Edmonds is the heir to the female branch of the McCaslin family tree, the Edmonds branch, just as Isaac is heir to the male, McCaslin, branch. When Carothers Edmonds kills the doe at the end of the story, it is a kind of act of self-obliteration.
The killing of the doe is also illegal and references the argument Edmonds has with Isaac over the nature of human moral behavior. Isaac, taking a more optimistic tone from his youthful obsession with historical shame and the curse of ownership, argues that people are essentially good but are held down by their circumstances. Edmonds argues that people behave because they are afraid of the police, afraid of punishment. By killing the doe, Carothers Edmonds steps outside that fear but without proving himself any better than his circumstances.