After Adam's funeral and Willie's funeral, Jack spends some time in Burden's Landing, spending his days quietly with Anne. They never discuss Willie's death or Adam's death; instead they sit wordlessly together, or Jack reads aloud from a book. Then one day Jack begins to wonder how Adam learned about Anne and Willie's affair. He asks her, but she says she does not know—a man called and told him, but she does not know who it was. Jack goes to visit Sadie Burke in the sanitarium where she has gone to recover her nerves. She tells Jack that Tiny Duffy (now the governor of the state) was the man who called Adam; and she confesses that Tiny learned about the affair from her. She was so angry about Willie leaving her to go back to Lucy that she told Tiny out of revenge, knowing that, by doing so, she was all but guaranteeing Willie's death. Jack blames Tiny rather than Sadie, and Sadie agrees to make a statement which Jack can use to bring about Tiny's downfall.
A week later, Duffy summons Jack to see him. He offers Jack his job back, with a substantial raise over Jack's already substantial income. Jack refuses, and tells Tiny he knows about his role in Willie's death. Tiny is stunned, and frightened, and when Jack leaves he feels heroic. But his feeling of moral heroism quickly dissolves into an acidic bitterness, because he realizes he is trying to make Tiny the sole villain as a way of denying his own share of responsibility. Jack withdraws into numbness, not even opening a letter from Anne when he receives it. He receives a letter from Sadie with her statement, saying that she is moving away and that she hopes Jack will let matters drop--Tiny has no chance to win the next gubernatorial election anyway, and if Jack pursues the matter Anne's name will be dragged through the mud. But Jack had already decided not to pursue it.
At the library Jack sees Sugar-Boy, and asks him what he would do if he learned that there was a man besides Adam who was responsible for Willie's death. Sugar-Boy says he would kill him, and Jack nearly tells him about Tiny's role. But he decides not to at the last second, and instead tells Sugar-Boy that it was a joke. Jack also goes to see Lucy, who has adopted Sibyl Frey's child, which she believes is Tom's. She tells Jack that Tom died of pneumonia shortly after the accident, and that the baby is the only thing that enabled her to live. She also tells him that she believes—and has to believe--that Willie was a great man. Jack says that he also believes it.
Jack goes to visit his mother at Burden's Landing, where he learns that she is leaving Theodore Murrell, the Young Executive. He is surprised to learn that she is doing so because she loved Judge Irwin all along. This knowledge changes Jack's long-held impression of his mother as a woman without a heart, and helps to shatter his belief in the Great Twitch. At the train station, he lies to his mother, and tells her that Judge Irwin killed himself not because of anything that Jack did, but because of his failing health. He thinks of this lie as his last gift to her.
After his mother leaves, he goes to visit Anne, and tells her the truth about his parentage. Eventually, he and Anne are married, and in the early part of 1939, when Jack is writing his story, they are living in Judge Irwin's house in Burden's Landing. The Scholarly Attorney, now frail and dying, lives with them. Jack is working on a book about Cass Mastern, whom he believes he can finally understand. After the old man dies and the book is finished, Jack says, he and Anne will leave Burden's Landing—stepping "out of history into history and the awful responsibility of Time."
In this chapter, Jack struggles through the chaos of recent events toward his final acceptance of responsibility and self-determination. In the aftermath of Willie Stark's death and his visits to Sadie, Jack's immediate reaction is to handle Willie's death the way he would have handled any other political problem encountered while working for Willie: get to the bottom of it, and then punish his enemies by blackmailing them. When he first learns from Sadie that Tiny informed Adam of Willie's affair with Anne, he visits Tiny and threatens him with the information--just as he used to threaten Willie's enemies with knowledge of their past misdeeds.
But Jack realizes something after his confrontation with Tiny that forces him to reassess his handling of the situation. He realizes that he has blamed Tiny in full for Willie's death, and that blaming Tiny is an admission that someone was directly responsible for what happened. If someone is responsible for an action, then the Great Twitch theory cannot hold up; and if someone is responsible for Willie's death, Jack is forced to face the measure of responsibility that he himself bears. Had he not told Anne about her father's role in Judge Irwin's bribe, Anne would not have become Willie's lover, and there would have been nothing for Tiny to provoke Adam with. Had he not convinced Adam to take the hospital job, Adam would not have been in the middle of a moral crisis that would have left him vulnerable to Tiny's manipulations. And so forth. (In fact, had Willie not ordered Jack to dig up information on Judge Irwin, the chain of events that led to his murder would never have been set into motion.)
Forced to confront his measure of responsibility for Willie's death, Jack descends into a numbness and abjures all human contact, even refusing to open a letter from Anne. But when he learns that his mother was truly in love with Judge Irwin, the knowledge that his mother was capable of love helps him to overcome his numbness, and to return to Anne. Out of tenderness, he takes in the Scholarly Attorney, the man who is not his father, and nurses him through his dying days. He marries Anne at last, and at the end of the novel, he has at last reopened Cass Mastern's papers, and begins to write the book that is a resumption of his PhD thesis.
The fact that Jack is now able to understand the sense of responsibility that defined Cass Mastern's life indicates that he is also able to accept responsibility for his own actions, and to accept the idea of responsibility generally. As the book closes, Jack says that he and Anne are preparing to move away from Burden's Landing—the place of their past—and into an uncertain future. In this future, they will understand and accept "the awful responsibility of Time"—the fact that each present action carries future consequences, which can in turn be traced back to causes in the past.