The teacher now places Tom next to Joe Harper. After trying to study for a while, Tom gives up and he and Joe play with the tick, each attempting to keep the bug on his side of the desk by harassing it with a pin. They begin arguing midway through the game, and the teacher again appears behind Tom, this time to deliver a tremendous whack to both boys.

During lunch, Tom and Becky sit in the empty schoolroom together, and Tom persuades her to “get engaged” to him—an agreement they render solemn by saying “I love you” and kissing. Tom begins talking excitedly about how much he enjoys being engaged and accidentally reveals that he was previously engaged to Amy Lawrence. Becky begins to cry and says that Tom must still love Amy. Tom denies it, swearing that he loves only Becky, but she cries harder and refuses to accept the brass andiron knob he offers her as a token of his affection. When Tom marches out, Becky realizes that he won’t return that day and becomes even more upset.

For the rest of the afternoon, Tom wanders about in a forest, first deciding that he will become a pirate, next trying a futile charm to locate his lost marbles, and finally encountering Joe Harper. The boys play Robin Hood and then go home, in agreement that “they would rather be outlaws a year in Sherwood Forest than President of the United States forever.”

That night, Tom sneaks out of bed and goes to the graveyard with Huck. They hide in a clump of elms a few feet from the fresh grave of Hoss Williams and wait for devils to appear. After a while, three figures approach the grave. The boys believe with a horrified delight that these are the devils, but they turn out to be three adults from the town carrying out a midnight mission of their own. Tom and Huck are surprised to discover the young Dr. Robinson accompanied by two local outcasts, the drunken Muff Potter and Injun Joe.

Dr. Robinson orders the other two men to dig up Hoss Williams’s corpse, presumably for use in medical experiments. After they finish the job, Potter demands extra payment, and Robinson refuses. Injun Joe then reminds Robinson of an incident that happened five years earlier, when Injun Joe came begging at the Robinsons’ kitchen door and was turned away. Injun Joe now intends to have his revenge. A fight ensues; Dr. Robinson knocks Injun Joe down and then is attacked by Potter. He uses Hoss Williams’s headstone to defend himself, knocking Potter unconscious. In the scuffle, Injun Joe stabs Dr. Robinson with Potter’s knife.

The terrified boys flee without being detected by the men. Eventually Potter awakens and asks Injun Joe what happened. Injun Joe tells the drunk Potter that Potter murdered Dr. Robinson in a drunken fury, and Potter, still dazed, believes him. Injun Joe promises not to tell anyone about the crime, and they part ways. Before Injun Joe leaves the graveyard, however, he notes smugly that Potter’s knife remains stuck in the corpse.

The boys run to a deserted tannery and hide, unaware of Injun Joe’s plot to blame Potter for the murder. They decide that if they tell what they saw and Injun Joe escapes hanging, he will probably kill them. Consequently, they decide to swear in blood never to tell anyone what they saw. After taking the oath, they hear the howls of a stray dog, which they interpret as a sign that whomever the animal is howling at will die. Tom and Huck assume the dog’s howls are for them, but when they go outside, they see that the dog is facing Muff Potter.

Tom goes home and crawls into bed. Sid, still awake, takes note of his late arrival and tells Aunt Polly about it the next morning. She lectures Tom and asks how he can go on breaking her heart; her heavy sorrow is for Tom a punishment “worse than a thousand whippings.” Tom goes off to school dejected. On his desk he finds the brass andiron knob he tried to give to Becky the day before, and his anguish deepens.

As his Robin Hood game shows, Tom assimilates and adheres to the conventions of the heroic and romantic stories in which he is so steeped. He memorizes situations and even exact dialogue from these stories in order to re-create them in his own games. Tom’s courtship of Becky also follows the conventions of romantic literature, albeit in a somewhat adulterated form.

With the ability to memorize and re-create situations according to stories and literature, Tom shows that he has highly developed mental skills. Yet, in his conduct and interaction with others, Tom is still immature. This imbalance is evident when Tom accidentally reveals his previous engagement to Amy Lawrence and only watches, unsure of how to act, when Becky cries. His subsequent depression and decision to become a pirate manifest his preference for the youthful world of make-believe and literature over that of real-life relationships. Tom’s actions at this point also foreshadow his later adventures with Huck and Joe on Jackson’s Island.

The graveyard scene constitutes a turning point in the plot, as it is the first of Tom’s adventures that has any moral significance. Up to this point, Tom’s adventures have been playful and innocent. As Tom and Huck witness Dr. Robinson’s murder, the sordid adult world imposes itself upon their childhood innocence. When they see the figures approaching the grave, both boys assume them to be devils, among the most terrifying things they can envision. Ironically, the presumed devils turn out to be real men who become more frightening than any childhood superstition or imagined vision.

After witnessing the crime, Tom and Huck’s immediate inclination is to flee, both physically and symbolically. They run from the scene of the crime back into their world of childhood games by signing a “blood oath” to keep what they have seen a secret. Knowing nothing about Injun Joe’s plan to blame hapless Muff Potter for the crime, Huck and Tom assume that Injun Joe will either be caught or will escape. They are understandably afraid of what these wicked men might do to them if they find out that the boys were present at the scene of the crime. As we later see, however, even after Potter is falsely accused and arrested, Tom and Huck are unable to overcome their fears and tell the authorities what they have seen. Instead, their belief in superstition, their adherence to the blood oath, and their assumption that God will strike down Injun Joe for wickedly lying guide their actions. Even though the boys fear Injun Joe, they also fear superstition and, ultimately, God or a higher force that they hope will cancel out the more immediate threat from the murderous Injun Joe.