The morning after Tom returns from the island, Aunt Polly rebukes him for having made her suffer so much and for not having given her some hint that he was not actually dead. Tom argues that doing so would have spoiled the whole adventure, but he admits that he “dreamed” about everyone back in town. Telling her his dream, Tom relates everything he saw and overheard when he crossed the river and sneaked into the house a few nights earlier. Aunt Polly seems amazed by the power of Tom’s vision and forgives him for not having visited her. Sid, meanwhile, wonders suspiciously how this dream could be so precise and detailed.

At school, Tom is declared a hero and basks in the adulation of his peers. He decides to ignore Becky and instead pays attention to Amy Lawrence again. When Becky realizes that he is ignoring her, she gets within earshot and begins issuing invitations to a picnic. Soon she has asked the whole class to come except Tom and Amy. They go off together, leaving Becky to stew in jealousy.

At recess, however, Becky manages to turn the tables by agreeing to look at a picture book with Alfred Temple, the new boy from the city with whom Tom fights at the beginning of the novel. Tom grows jealous and becomes bored with Amy. With a great sense of relief, he heads home alone for lunch. Once Tom is gone, Becky drops Alfred, who, when he realizes what has transpired, pours ink on Tom’s spelling book to get him in trouble. Becky sees Alfred commit the act and considers warning Tom in the hopes of mending their troubles. But, overcome by Tom’s recent cruelness to her, she decides instead that Tom deserves a whipping and that she will hate him forever.

Back home, Aunt Polly has learned from Mrs. Harper that Tom’s dream was a fake and that he came home one night and spied on them. Aunt Polly scolds him for making her look like a fool in front of Mrs. Harper and then asks why he came home but still did nothing to relieve everyone’s sorrow. Tom replies that he was going to leave a message for her, but he was afraid it would spoil the surprise, so he left it in his pocket. She sends him back to school and goes to look in the jacket that he wore to Jackson’s Island, resolving not to be angry if the message is not there. When she finds it, she breaks down in tears and says, “I could forgive the boy, now, if he’d committed a million sins!”

Back at school, Tom attempts a reconciliation with Becky, but she blows him off and looks forward to seeing him whipped for the inky spelling book. She proceeds to find a key in the lock of the teacher’s desk drawer; the drawer contains a book that only the teacher, Mr. Dobbins, is allowed to read. She opens it and discovers that it is an anatomy textbook that Mr. Dobbins possesses since his true ambition is to be a doctor. She opens it to the front page, which shows a naked figure, and at that moment Tom enters. His entry startles her so much that she rips the page. She begins to cry, blames him for making her rip it, and realizes now that she will be whipped.

The class files in, and Tom stands stoically for his own whipping, assuming that he must have spilled the ink himself accidentally. Mr. Dobbins finds the ripped book and begins to grill each member of the class in turn. When he reaches Becky, she seems ready to break down, but she is saved when Tom rises and declares, “I done it!”—thus incurring a second whipping but becoming a hero again in Becky’s eyes.

In these chapters, Tom fluctuates between petty, immature behavior—lying to his aunt about his alleged dream and trying to make Becky jealous at the expense of Amy’s feelings—and nobler conduct—saving Becky from punishment. The fact that Tom’s story about his dream fools his aunt but not Sid may ironically indicate that in some way children are more perceptive than adults. On the other hand, perhaps Aunt Polly is deceived because true maturity includes love and the forgiveness that comes along with it. Perhaps Sid is too morally immature to understand that such trickery is excusable in a person that one loves.

Once Tom realizes the damage he has done, he feels remorse for the second time in the novel, which indicates that his moral growth is continuing. He feels genuine affection for Aunt Polly and wants to secure her approval. His manipulation of her seems to happen almost instinctively, as he gets carried away by his own flights of fancy.

The snubbing war between Tom and Becky forms a counterpart to the make-believe military battle fought between generals Tom and Joe early in the novel. Descriptions of the elaborate strategies Tom and Becky employ to make each other jealous make up the bulk of these chapters. Both behave in a petty, childish fashion, trying to prove to one another how little each needs the other. Until Tom takes Becky’s punishment, the two remain trapped in this cycle of nasty behavior. Tom’s act of self-sacrifice breaks the cycle and enables the pair to reunite. By taking Becky’s whipping and winning her back, Tom also brings his pirate adventure to its full conclusion, since it begins with Becky’s rejection of him.

Twain directs our sympathy in these chapters toward Amy and Alfred, whom Tom and Becky use and then discard. Both characters, who vanish from the novel after Chapter 18, remain tools. Not only are they tools for Tom and Becky in their love war, but they are also rather dull characters for Twain himself—he doesn’t even consider going beyond the letter “A” in giving them names. Mr. Dobbins too serves as nothing more than a tool for Tom’s development. Mr. Dobbins’s threatening authority, although undermined in our eyes by the discovery of his secret desire to be a doctor and his humorous obsession with his medical textbook, allows Tom a chance to act heroically.