In chapter five Huck talks to his Pap, who is around fifty years old and looks homeless. His father is angry that he's been attending school because he doesn't want to have a son who knows more than he does. His dad is also very interested in obtaining Huck's money, which people throughout the county have been talking about. Huck claims he gave it to Judge Thatcher, but his dad doesn't believe him. Pap insists that Huck get him the money and stop attending school. Then he decides to try to get guardianship of Huck back, so he goes before the court who agrees to give Huck back to his father because the courts didn't like to take children away from their parents in those days. This new judge decides to take Pap home with him to help him straighten out, but Pap ends up robbing the judge, becoming extremely drunk, and breaking his arm. The judge gives up on reforming Pap.

Chapter six has Pap away from civilization to a cabin on the Illinois shore, which leads the reader to believe that Huck must have originally resided in Missouri, and they travel on the Mississippi River. Pap treats Huck like a prisoner while they live there. He beats him periodically and locks him in whenever he leaves for supplies. Huck enjoys the lazy, carefree life, but dislikes being hit by his father, so he eventually decides he needs to escape. He finds a rusty wood-saw and cuts out a small section of the log cabin wall that he covers with a blanket when his father is around. One night Pap gets really drunk and starts ranting about how the government is giving too many rights to blacks and mulattos. He eventually starts hallucinating and chasing Huck around the cabin with a knife. Huck avoids him until his dad eventually passes out at which point Huck grabs their shotgun and keeps it pointed at his father in case he wakes up wanting to hurt him again.

At the start of chapter seven Pap awakes to see Huck pointing the gun at him, so Huck has to lie and say that someone had attempted to break in to their cabin. When Pap leaves for supplies, Huck sneaks out and happens to find a canoe drifting by. He takes it and hides it then comes up with a plan for escaping in such a way that no one will come looking for him. When Pap leaves again the next night, Huck takes a bunch of their food supplies and drags them into the canoe. He kills a wild pig wandering by and smears its blood from the cabin into the woods. He also smears some blood on the axe that he used to smash in the door of the cabin and put in the corner. After tearing a hole in the bag of cornmeal, he leaves a trail leading into the woods then seals it up and puts it in the canoe. Once in the canoe, he floats down the river toward Jackson's Island. On the way, he falls asleep and then wakes up to find Pap drifting past him on their raft in the other direction. Luckily, it was so dark that Pap didn't see him. Huck arrives at the island and ties up the canoe before taking a nap.

In chapter eight Huck rouses to the sound of a cannon going off. He peeks out and sees his family and friends floating by on a ferry-boat shooting off a cannon in the hopes of raising his dead body to the surface of the water. Huck feels safe knowing that Pap, the widow, and everyone who knows him thinks he is dead, so they will no longer be looking for him. Later he comes across the ashes of a recent camp fire and realizes that someone else is living on the island too; it's Jim. At first Jim thinks Huck is a ghost because he heard he had died, but once Huck convinces him that he's alive, Jim is glad to see him. Jim explains that he ran off from Miss Watson since he overheard her talking about selling him down to New Orleans because she could get $800 for him. Then Jim and Huck have a conversation about money that shows that Jim has had very little experience with it.

These chapters make the setting of the book more clear. Since slavery was abolished in 1868, the book must be taking place prior to that since Jim is a slave. It also shows the unlikely friendship between a young white man and an older black man, both on the run, and neither of whom should be traveling unaccompanied, yet they will be able to assist one another in many ways.