Set in the pre-Civil War American South, the story follows Huckleberry "Huck" Finn, Eddie Hodges, a restless boy living in the fictional town of St. Petersburg, Missouri, along the Mississippi River. Huck has been taken in by the Widow Douglas, Josephine Hutchinson, and her sister, Miss Watson, who aim to "sivilize" him by teaching him manners, religion, and education. Despite their efforts, Huck remains restless and dreams of living free from adult rules and the structure of society.
Huck’s peace is disrupted when his alcoholic and abusive father, Pap Finn, Neville Brand, returns to town. Having heard of Huck’s wealth from a previous adventure, Pap demands custody of his son. The court, swayed by Pap’s manipulations, grants him custody. Huck is taken to a remote cabin deep in the woods, where he is locked away and physically abused. Wanting to escape both his father and the constraints of civilization, Huck stages his own murder using a pig’s blood and flees to Jackson's Island, an isolated stretch of land in the Mississippi River.
While hiding out on the island, Huck discovers Jim, Archie Moore Miss Watson’s enslaved servant, who has also run away after learning he’s to be sold to a plantation in the Deep South. At first, Huck is shocked. He has been raised to see helping a runaway slave as wrong. However, as they spend time together, Huck begins to view Jim not as property, but as a human being and a friend. Jim shares his plan to travel north, eventually to Cairo, Illinois, where he hopes to earn enough money to buy his family’s freedom.
Huck and Jim construct a raft and begin their journey down the Mississippi River, seeking freedom and escape from their respective troubles. Along the way, they encounter both danger and deception, testing the strength of their bond and Huck’s growing moral awareness.
One of their early adventures occurs when they come across a house floating in the river. Inside, they find a dead body. Jim refuses to let Huck look at the face, claiming it’s too gruesome. Later, it is revealed that the body was Pap Finn’s, although Jim keeps this from Huck to protect him.
Further downriver, they meet two men on the run: a pair of confidence tricksters who claim to be a displaced English duke and the long-lost French king. Though Huck recognizes them as frauds, he and Jim allow them to stay aboard the raft to avoid trouble. The conmen's schemes grow more elaborate and dangerous as they stop in various towns to perform fake Shakespearean plays and swindle money from grieving families.
Their most elaborate scam takes place when they pretend to be the long-lost brothers of Peter Wilks, a recently deceased man who left behind a fortune. The town initially believes their story, but Huck, moved by the kindness of Wilks’s nieces—Mary Jane Sherry Jackson, Joanna Patty McCormack, and Susan—secretly hides the money the conmen plan to steal. The arrival of the real brothers leads to the exposure of the frauds, and the duke and the king barely escape from an angry mob.
Soon after, the conmen betray Huck and sell Jim to the Phelps family, claiming he is a runaway slave in exchange for a reward. The Phelpses, who turn out to be relatives of Huck’s friend Tom Sawyer, intend to return Jim to his owner. Huck now faces a moral crisis. Although society has taught him that helping a slave escape is wrong, he cannot abandon his friend.
Determined to rescue Jim, Huck devises a plan. He disguises himself and sneaks onto the Phelps property, where Jim is locked in a shed. After writing a letter to Miss Watson revealing Jim’s location, Huck has a moral epiphany. He tears up the letter and decides, “All right, then, I’ll go to hell”—choosing to help Jim rather than conform to society’s racist values.
Meanwhile, the king and duke get into trouble once again and are captured after trying to run another scam. With their arrest providing a diversion, Huck manages to free Jim, and the two escape back to the raft.
Later, Jim reveals that the dead man in the floating house was Pap Finn—meaning Huck is now free from his abusive father. They also learn that Miss Watson had died and, in her will, granted Jim his freedom. Though their journey was dangerous and at times unnecessary in a legal sense, it was deeply transformative.
Jim continues north to find his family, and Huck, rejecting the idea of returning to civilization and being “sivilized” again, decides to “light out for the Territory” in search of freedom and adventure.
