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 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.