Summer has almost arrived and the schoolchildren are restless. Mr. Dobbins becomes even more harsh in his discipline, provoking the boys to conspire against him. At the end of the year, the town gathers in the schoolhouse for the “Examination,” in which students recite speeches and poems and engage in spelling and geography competitions. Tom struggles through “Give me liberty or give me death,” finally succumbing to stage fright, and a series of young ladies then recites the hilariously awful poems and essays they have written. Finally, the schoolmaster turns to the blackboard to draw a map of the United States for the geography class, and at that moment a blindfolded cat is lowered from the rafters by a string. The animal claws at the air and yanks off Mr. Dobbins’s wig, revealing a bald head that the sign-painter’s boy gilded while Mr. Dobbins slept off a bout of drinking.

At the beginning of summer, Tom joins the Cadets of Temperance in order to wear one of their showy uniforms. Unfortunately, to join he must swear off smoking, tobacco chewing, and cursing—prohibitions that prove very difficult. He resolves to hang on until Judge Frazier, the justice of the peace, dies, because then he can wear his red sash in the public funeral. When the judge recovers, Tom resigns from the Cadets. The judge suffers a relapse and dies that night.

Vacation begins to drag. Becky Thatcher has gone to the town of Constantinople to stay with her parents, and the various circuses, parades, and minstrel shows that pass through town provide only temporary entertainment. The secret of Dr. Robinson’s murder still tugs at Tom’s conscience. Tom then gets the measles, and when he begins to recover, he discovers that a revival has swept through the town, leaving all his friends suddenly religious. That night brings a terrible thunderstorm, which Tom assumes must be directed at him as punishment for his sinful ways. The next day he has a relapse of the measles and stays in bed for three weeks. When he is finally on his feet again, Tom finds that all his friends have reverted to their former, impious ways.

Muff Potter’s trial approaches, and Tom and Huck agonize about whether they should reveal what they know. They agree that Injun Joe would kill them, so they continue to help Potter in small ways, bringing him tobacco and matches and feeling guilty when he thanks them for their friendship. The trial finally arrives, and Injun Joe gives his account of the events. A series of witnesses testifies to Potter’s peculiar behavior, and in each case Potter’s lawyer declines to cross-examine. Finally, Potter’s lawyer calls Tom Sawyer as a witness for the defense, much to everyone’s amazement. Tom, deeply frightened, takes the witness stand and tells the court what he saw that night. When he reaches the point in the story where Injun Joe stabs the doctor, Injun Joe leaps from his seat, pulls free of everyone, and escapes through a window.

Tom is acclaimed as a hero and enjoys the adulation and gratitude of Muff Potter and the rest of the town during the day. At night, however, he is tormented by visions of Injun Joe coming to kill him. Injun Joe has vanished, despite the town’s and a detective’s best efforts to locate and capture him.

Mr. Dobbins’s humiliation at the hands of the sign-painter’s boy and the revelation that he drinks too much links him with the Sunday school superintendent and the minister as a person in a position of power who falls victim to Twain’s deft satire. Dobbins is a prime example of an authority figure who, ironically, has no true authority, because he is clearly dissatisfied with who he is. Both Mr. Dobbins’s obsession with his anatomy textbook and his false hair manifest his desire to be something that he is not.

In a footnote, Twain claims that the flowery, overstated compositions presented in the Examination scene are not his own creations but rather “are taken without alteration from a volume entitled ‘Prose and Poetry, by a Western Lady.’” One composition begins “Dark and tempestuous was night” in a pretentious version of the clichéd first line, “It was a dark and stormy night.” Twain is criticizing the shallowness of small-town intellectual pretension, but his footnote suggests that his criticism is specifically directed toward women, and this scene is somewhat misogynistic (woman-hating). However one may interpret it, the Examination scene criticizes the same flaw to which the character of Dobbins falls prey: trying to be something one is not.

Like the Sunday school scene in which Tom claims a Bible, Twain ends the Examination chapter with a shocking event—the cat lifting the wig—but avoids describing the event’s aftermath. There may be several reasons for Twain’s omission of the specifics, but one explanation concerns the novel’s universality. Twain’s criticism is generally directed toward universal human foibles; importantly, he leave blanks for us to fill in, so that each reader ponders the events within his or her own frame of reference.

In Chapter 22, Twain again pokes fun at the fickleness of the townspeople’s religious belief. When a revival sweeps town, all the boys “get religion,” but they go back to their old ways within a few weeks. Tom’s understanding of God evolves out of his superstitious way of viewing the world—when a thunderstorm strikes, he believes that God has aimed it at him as a personal punishment.

Tom’s decision to testify at Muff Potter’s trial marks an important moment in his process of maturation from childhood to adulthood. His fear for his physical safety and his superstitious unwillingness to go back on his blood oath with Joe Harper are what have kept him from doing the right thing. Both are sentiments associated with childhood. While Twain does not give us a direct depiction of Tom’s internal moral crisis, he builds an atmosphere of increasing anxiety and indicates that Tom’s silence may have serious implications for the wrongly accused Muff Potter. When Tom eventually changes his priorities and acts out of his concern for Muff instead of out of his concern for himself, he conquers his fear and achieves a greater level of maturity.

If Tom Sawyer were a simple bildungsroman, a narrative of moral and psychological growth, then Tom’s decision to testify would be an appropriate ending. However, Tom Sawyer is also an adventure story, and to add suspense and danger to the plot, Twain allows Injun Joe to escape. Psychologically, Tom may be on the road to adulthood, but he still has to conquer Injun Joe outside the courtroom before his adventures can conclude.