Dawson's Landing is in a state of excitement from the recent events. The twins are heroes, the duel a success in the public opinion, and Pudd'nhead Wilson, thanks to his friendship with the twins, is the favorite to become mayor. "Tom" encounters the constable and Pudd'nhead on the street and rather unkindly asks the constable if he's caught the old woman responsible for the robberies yet. He asks Pudd'nhead, equally snidely, if his trap to catch the thief has worked yet. He then tells the men what he has guessed about the trap (which is actually Roxy's supposition): that the reward for the knife is public knowledge while the reward for the thief isn't, and that they are expecting the thief to turn in the knife for the reward, claiming he found it or bought it. "Tom" then claims that there is no knife, that the twins made up the knife in order to offer a reward that will never have to be paid. Their generosity and the exotic story would then make them even more popular in the town. The constable is convinced by "Tom"'s theory, and even Pudd'nhead begins to wonder about the twins.
"Tom" makes amends with Judge Driscoll by telling him that he had not wanted to duel with Luigi because he knew that Luigi was a murderer. He tells him that he would have stopped the judge from making the challenge if he had known, and the judge thanks him for respecting the family's honor by not wanting to fight with a criminal. The judge vows to embarrass the twins and shoot Luigi. Both the judge and Roxy are happy with "Tom"'s good behavior. He departs for St. Louis to sell some of the stolen goods, but is robbed of them aboard the riverboat. Roxy follows him to St. Louis and, upon finding out what has happened, is so concerned about her son's fate that she tells him to sell her as a slave to someone in the area. "Tom" sells her instead to a planter from Arkansas, lying to her that she's going to a nearby farm and that he will buy her back in a year. He pays off his debts and soon feels at ease about what he's done. Roxy, having worked on riverboats for many years, soon realizes when she sets out with her new owner that she has been sold "down the river" by her own son. She is distraught.
Back in Dawson's Landing, political campaigns have begun. The twins are running for seats as councilmen. Judge Driscoll and "Tom" work against them, and the judge is so happy with "Tom"'s improved behavior that he even gives him the combination to the safe and responsibility for buying votes. In the last speech of the campaign the judge slams the twins as con-artists, sideshow freaks, and criminals. He airs the accusation about the non-existent knife, and hints at Luigi's murderous past. The crowd is impressed. The twins lose the election, but Pudd'nhead is still elected mayor. Rumors soon spread that Luigi will challenge the judge to another duel once the judge has recovered from the election. "Tom" returns to St. Louis happy with his efforts.
The comedy comes to a halt in this section with "Tom"'s sale of his mother "down the river." The bitter irony in this, of course, is that Roxy, who is a free woman, has been sold by her son, who is really a slave. Roxy has been blackmailing "Tom" with this information, though, and perhaps now that she is out of the way "Tom" will be able to reform himself successfully, as a sort of born- again "white" man. Roxy's sale is most important, however, because it reminds the reader what has motivated all of her actions: her fear that "Tom" would be sold "down the river." The manipulations of "Tom"'s identity may have made him into an immoral, mean-spirited person, but perhaps the loss of his soul is preferable to the loss of his whole self to a planter in the deep South. Perhaps Twain is suggesting that no good solution exists within the system of slavery: to save oneself one is forced to sin. Roxy is even willing to see herself sold rather than lose her son.
The fate of the twins in the election deepens the problem with identity and draws the novel further into the genre of the detective story. Although he is acting on faulty information coming from "Tom," the judge, in his election-day speech, voices many of the reader's suspicions about the twins. Just who are they, really, and why have they come to Dawson's Landing? And are their stories true? Even Pudd'nhead, with no better information to go on, has been forced to suspect them. It is "Tom"'s identity that is the most questionable here, of course, but Roxy seems to have committed the perfect crime and no one sees any reason to question "Tom." The twins call into question the possibility of "reading" accurately: it is not clear whether anyone is interpreting them correctly, or whether anyone, even Pudd'nhead, is capable of doing so. Pudd'nhead seems to be playing a deep game, though, and he may know more than he is letting on. The election is a vote of confidence in the judge, Pudd'nhead, and the twins, and while Pudd'nhead may have risen in the public estimation, the twins are beginning to look suspicious. The opinion of the judge and Pudd'nhead is enough to convince the townspeople; should it convince the reader too?