Terrified, Tom and Huck flee the graveyard. They stop at an abandoned cottage. They agree not to tell what they've seen for fear Injun Joe will kill them. They sign a pledge of secrecy in blood and bury it.
Though they've just seen a horrific act of lying, the boys decide they'll continue lying. They have their own good in mind, rather than Muff Potter's, or the villagers', for that matter.
The sound of movement frightens the boys. It turns out to be a dog. As they are interpreting this omen, they notice the sound of snoring. The source is Muff Potter. Sighting the dog by Muff's body, they conjecture more about its significance, arguing over whether it means Muff is a "goner" as they head home.
The boys might have told Muff of about Injun Joe's treachery, but they distract themselves with their superstitious beliefs. They should act responsibly to deal with the serious new reality they are faced with, but instead they retreat into their romantic world, believing that another magical event, or the will of God, will intervene to save Muff.
The next morning, Tom wonders why he has been allowed to sleep in. Over breakfast, his family is solemn. Afterwards Aunt Polly pulls him aside, and Tom learns that Sid betrayed him. She weeps that Tom disobeyed her by sneaking out. She's so overwhelmed with disappointment that she doesn't bother whipping him.
Aunt Polly once again fails to follow the rules of punishment she has laid out to Tom, even as she punishes him for breaking rules. Her grief is real, however, and Tom is sensitive to its seriousness in a new way that suggests he has been changed by the murder he witnessed the previous night.
Tom heads to school, forlorn at having distressed Aunt Polly. His grief is worsened when he finds his brass andiron knob on his desk, returned by Becky.
The evidence of how he has hurt others depresses Tom, revealing that he is growing up a little.