Huckleberry Finn introduces himself as a character from the book prequel to his own, The Adventures of Tom Sawyer. He explains that at the end of that book, he and his friend Tom Sawyer discovered a robber’s cache of gold and consequently became rich, but that now Huck lives with a good but mechanical woman, the Widow Douglas, and her holier-than-thou sister, Miss Watson.
Huck resents the “sivilized” lifestyle that the widow imposes on him. However, Huck stays with the Widow and Miss Watson because Tom tells him that, if Huck doesn’t stick with his life in straight-laced civilization, he can’t join Tom’s gang. So Huck does as the Widow tells him and gets to play robbers with Tom and other boys once in a while.
Even as Huck grows to enjoy his lifestyle with the Widow, his debauched father Pap menacingly reappears one night in his room. Pap rebukes Huck for trying to better his life and demands that Huck give him the fortune he made after discovering the robber’s gold. Huck goes about business as usual as the Widow and a local judge, Judge Thatcher, try to get custody of him so that he doesn’t fall into his father’s incapable and cruel hands. However, the two fail in their custody battle, and an infuriated Pap decides to kidnap his son and drag him across the Mississippi River to an isolated cabin.
Huck is locked up like a prisoner in the cabin, and he is at the mercy of Pap’s drunken, murderous rages, suffering many beatings from the old man. Huck resolves to escape from Pap once and for all. After some preparation, he fakes his own death. Afterwards, Huck canoes to a place called Jackson’s Island, where he finds a man he knows from home, a slave named Jim who has run away from his owner, Miss Watson, because he had overheard that she planned to sell him.
Having found a raft during a storm, Huck and Jim happily inhabit Jackson’s Island, fishing, lazing, and even investigating a house floating down the river that contained a dead body. However, during trip into town while disguised as a girl to gather information, Huck learns that slave-hunters are out to capture Jim for a reward. He and Jim quit the island on their raft, with the free states as their destination.
A few days in, a fog descends on the river such that Huck and Jim miss their route to the free states. In the aftermath of this fog, Huck struggles with the command of his conscience to turn Jim in and the cry of his heart to aid Jim in his bid for freedom. At last, Huck has his chance to turn Jim in, but he declines to do so. The night after, a steamboat ploughs into Huck and Jim’s raft, separating the two.
Huck washes up in front of the house of an aristocratic family, the Grangerfords, which takes Huck into its hospitality. But the Grangerfords are engaged in an absurdly pointless and devastating feud with a rival family, the Shepherdsons. When a Grangerford girl elopes with a Shepherdson boy, the feud escalates to mad bloodshed. Huck, having learned that Jim is in hiding nearby with the repaired raft, barely escapes from the carnage. He and Jim board the raft and continue to drift downriver.
A few days pass before Huck and Jim find two con men on the run. Huck helps the men escape their pursuers and he and Jim host them on the raft, where one of the con men claims to be a duke and the other a king. The duke and king take advantage of Huck and Jim’s hospitality, taking over their raft as they head downriver, all the while conducting scams on shore.
One day, the king learns that a man nearby, Peter Wilks, has died, and that his brothers are expected to arrive. Hoping to collect the man’s inheritance, the duke and king go to his house claiming to be his dear brothers. Though they ingratiate themselves with most of the townspeople, especially Peter’s nieces, the duke and king are suspected by some of being frauds. Huck comes to feel so bad for Peter’s nieces, though, that he resolves to expose the con men for what they are. As he puts his plan into effect, Peter’s real brothers arrive, and, after the townspeople investigate, the duke and king are exposed. Huck escapes onto the raft with Jim, but despairs when the duke and king manage to do the same.
Desperate for money, the duke and king sell Jim to a local farmer, Silas Phelps, claiming that Jim is a runaway and that there is a reward on his head. The duke betrays to Huck that Jim is being held at the Phelps farm. After some soul-searching, Huck decides that he would rather save Jim and go to hell than to let his friend be returned to bondage.
Huck arrives at the Phelps farm where he meets Aunt Sally, whom Huck tricks into thinking that Huck is a family member she was expecting, named Tom. Soon, though, Huck learns that Uncle Silas and Aunt Sally are none other than Tom Sawyer’s relatives. Indeed, Tom is the family member Aunt Sally was expecting all along. Huck intercepts Tom as he rides up to the Phelps farm, and Tom not only agrees to help Huck keep his cover by impersonating his cousin Sid, but he also agrees to help Huck in helping Jim escape from captivity.
Tom confabulates an impractical, romantic plan to free Jim, which Huck and Jim reluctantly go along with. One night, Jim, Huck, and Tom make a successful break for the Mississippi River, only to learn, however, that Tom was shot in the leg by one of their pursuers. Jim sacrifices his freedom to wait with Tom while Huck fetches a doctor, who, after treating Tom with Jim’s help, insists on bringing Jim back to the Phelps farm, bound. He also presents Tom to the Phelpses wounded but alive.
After he recovers, Tom reveals to an anxious Aunt Sally and Huck that Miss Watson wrote in her will that Jim was to be freed after her death and that she had died two months earlier. Tom wanted to liberate Jim for the sake of self-indulgent adventure.
After things are straightened out, Jim reveals to Huck that Pap is dead; his was the corpse that Jim discovered in the floating house. Huck also learns that he still has six thousand dollars in Judge Thatcher’s safekeeping and is free to do what he wants. Fearful of being adopted by Aunt Sally and “sivilized” again, Huck decides that he is going to go West.
