In chapter one, the first person narrator, Huckleberry Finn, introduces himself and talks to the readers about his appearance in the prequel to this book The Adventures of Tom Sawyer by Mark Twain. He then summarizes how that book ends, which is that he and his pal Tom found $12,000 in gold that robbers had hidden in a cave. They split the money, invested it, and each make a dollar a day in interest off of their findings. Huck lives with the Widow Douglas who wants him to be civilized and respectable, which Huck doesn't like. The widow tries to impart religion into Huck, but he doesn't take to that either. The widow lives with her sister Miss Watson who also attempts to make Huck a better person. He is quite superstitious and believes that events, such as accidentally flipping a spider into a candle will bring him bad luck. Tom appears outside Huck's window that night and meows, which is their sign for Huck to climb out of his bedroom window and sneak away with Tom.

In chapter two, Huck and Tom are trying to sneak away from the house. They come across Miss Watson's slave, Jim, and are forced to freeze in their tracks until Jim falls asleep. Then Tom wants to play a trick on Jim, so Tom takes Jim's hat and hangs it on the tree limb above his head. When Jim wakes up, he tells everyone that witches visited him and flew him around the country. He uses the nickel that Tom left in the kitchen to pay for the candle he stole from the widow as proof of the witches, and blacks from all around town come to see Jim's five-center piece, which he wears around his neck. Huck and Tom grab a few more friends and take them to a cave down the river where they decide to form Tom Sawyer's gang, which is more of a childish club. They make up the rules for their gang, sign their names in blood, and discuss what their gang should do. Tom, who gets all of his information from the books that he reads, tells the gang that they will need to stop carriages to capture people and steal their money. Tom explains that they can ransom the women, since it isn't proper to kill them, and the boys discuss the logistics of where to keep these prisoners and what exactly it means to "ransom" someone, which clearly none of them actually understand. One little boy falls asleep and another begins to cry, so they agree to head home and meet again soon.

In chapter three, Huck talks about his dad, Pap, whom Huck hasn't seen in more than a year. He is an abusive alcoholic whom many people in town believe is dead. The boys meet up to rob a church picnic, which Tom swears is a group of Spanish merchants and rich Arabs in disguise, but Huck knows that Tom likes to exaggerate. There's a nice allusion to "Don Quixote," a man known for a vivid imagination, who Tom ironically mentions to Huck since Tom is actually a quixotic character himself. Tom tells Huck the story of the genie in the lamp, so Huck heads home to rub an old tin lamp hoping to find a genie without any success.

Four months pass when chapter four begins during which Huck has been attending school. On the snow fall, he sees boot tracks with a cross in the left heel, and he knows that means his Pap is back. He hurries to Judge Thatcher, who is in charge of his money, and asks him to take all of his money, so Judge Thatcher allows Huck to sell it to him for a dollar. When he gets back to his room, Huck finds his dad sitting on his bed. In this chapter Huck also describes Jim's hair-ball, which came from the stomach of an ox and can supposedly tell people's fortunes. Huck pays Jim to talk to the hair-ball and tell his future, which Jim does in a typical generic fortune-telling way. He mentions that Huck's father has a white angel and a black angel on his shoulder telling him what to do, so sometimes he makes good choices and sometimes his choices are bad. Then he tells Huck that he will have good times and bad in his life and that he should stay away from water.

The reader should question whether Huck is reliable narrator for the novel due to his age and ignorance. Huck appears to be a kind person who wants to please others, but perhaps he isn't telling the story exactly as it happened. Even though he has had a difficult childhood, he seems to be forming a decent moral compass. The use of the word "nigger" makes it clear that the setting of the book is over fifty years ago, likely much further back than that. Huck will likely be an archetypal hero in this book as he goes on adventures with his friend Tom or on his own.