They take refuge in the abandoned tannery, a curiously spooky place to hide after witnessing a murder.
The boys want to tell the authorities what happened, but they know that Injun Joe will come after them if they do.
They decide to keep their traps shut.
In order to make sure that they're not tempted to tell, they write up a contract and seal the deal in blood…yes, blood.
Soon after they hear a stray dog howl – which apparently means one of them is going to die; the two promise to change their ways if they survive, until they notice that the dog's got its back to them. Apparently that means they're in the clear.
Just then they hear another sound – somebody's snoring.
They find Muff Potter sleeping in the corner…and the stray dog is facing right toward him. That's a bad sign for Muff.
They try to reassure themselves that such silly superstitions don't mean anything – but they've heard slaves talk about these things, and slaves know what's up when it comes to superstitions.
The two boys part ways, and Tom sneaks back into his bedroom.
When he comes down the next morning, he finds his family looking terribly sad. After breakfast, Aunt Polly lets him know how awful he's made her feel.
Tom begs her forgiveness, but leaves for school feeling terrible.
After he and Joe Harper get flogged for playing hooky, Tom sits down and stews in his misery for a while.
Just then he notices his brass knob sitting on the desk, and he's thrown into a deeper, darker mood.