In post-World War II Rome, Antonio Ricci desperately needs work to support his wife Maria, his son Bruno and his small baby. He is offered a job posting advertising bills but tells Maria he cannot accept because the job requires a bicycle. Maria resolutely strips the bed of her dowry bedsheets — prized possessions for a poor family — and takes them to the pawn shop, where they bring enough to redeem Antonio's bicycle. On his first day of work, Antonio is at the top of a ladder when a young man steals his bicycle. Antonio runs after him but is thrown off the trail by the thief's confederates. The police file Antonio's complaint but say that there is little they can do. Advised that stolen goods often surface at the Piazza Vittorio market, Antonio and his son go there with several friends. They find a bicycle frame that might be Antonio's, but the vendors refuse to allow them to examine the serial number. They call over a carabiniere, who orders the vendors to allow him to read the serial number. It does not match that of the missing bicycle, but the officer won't allow them to examine it for themselves. At the Porta Portese market, Antonio and Bruno spot someone he believes to be the thief with an old man. The thief eludes them and the old man feigns ignorance. They follow him into a church where he too slips away from them. Antonio pursues the thief into a brothel, whose denizens eject them. In the street, hostile neighbors gather as Antonio accuses the thief, who conveniently falls into a fit for which the crowd blames Antonio. Bruno fetches a policeman, who searches the thief's apartment without success. The policeman tells Antonio the case is weak — Antonio has no witnesses and the neighbors are certain to provide the thief with an alibi. Antonio and Bruno leave in despair amid jeers and threats from the crowd. Their way home takes them to the Stadio Nazionale PNF football stadium. Antonio sees an unattended bicycle near a doorway and after much anguished indecision, instructs Bruno to take the tram to a stop nearby and wait. Antonio circles the unattended bicycle and jumps on it. Instantly, the hue and cry is raised and Bruno—who has missed the tram—is stunned to see his father pursued, surrounded and pulled from the bicycle. As Antonio is being muscled toward the police station, the bicycle's owner notices Bruno in tears and, in a moment of compassion, tells the others to release Antonio. Antonio and Bruno then walk off slowly amid a buffeting crowd. Antonio fights back tears and Bruno takes his hand.

In April 1992, Chris McCandless arrives in a remote area called Healy, just north of Denali National Park and Preserve in Alaska. Noting McCandless's unpreparedness, the man who drops him off gives him gumboots. McCandless sets up camp in an abandoned city bus that he calls "The Magic Bus". He is content with the isolation, the beauty of nature, and the thrill of living off the land. He hunts with a.22 rifle, reads books, and keeps a journal as he prepares his new life in the wild.

Billy Madison is a dimwitted, immature, and spoiled 27-year-old heir to Madison Hotels, a Fortune 500 company founded by his father, Brian Madison. Rather than preparing to take over the family business, Billy spends his days partying with friends and causing chaos on the estate. After he embarrasses his father during an important dinner meeting, Brian, who is retiring soon, decides to hand control of the company to his conniving vice president, Eric Gordon. When Billy pleads for another chance, Brian reveals that he bribed teachers to help Billy pass school. The two strike a deal: Billy must complete grades 1 through 12, spending two weeks on each grade, to prove he is capable of running the company. Billy returns to elementary school, where he gradually earns the respect of his classmates and third grade teacher, Veronica Vaughn, especially after standing up for a fellow student. Billy's rapid academic progress alarms Eric, who learns elementary school principal Max Anderson was once the professional wrestler called "the Revolting Blob", who accidentally killed an opponent in the ring. He uses this knowledge to blackmail Max into falsely claiming that Billy bribed him. As a result, Brian cancels the agreement and reinstates Eric as his successor. Discouraged, Billy drops out, but Veronica and his former classmates convince him to return. Max later confesses the truth, and Brian allows Billy to resume the challenge. When Eric objects, Billy proposes an academic decathlon to settle the matter. After a series of competitive events, Billy takes a narrow lead. In the final round—a Jeopardy! -style quiz—Eric selects "reflections of society in literature" for Billy's final category. Billy fumbles his answer but selects " business ethics " for Eric's final category. Unable to respond, Eric suffers a breakdown, pulls a gun on Billy, and is stopped by Max, who dons his Revolting Blob costume. Eric then attempts to harm Veronica but is shot by Danny McGrath, a former classmate Billy once bullied and later apologized to. At graduation, Billy announces that he will not take over Madison Hotels, but instead, he entrusts the company to loyal operations manager Carl Alphonse. Billy expresses his desire to go to college and pursue a teaching career, while a defeated and injured Eric watches in frustration.

At William Bloom's wedding party, his father Edward recalls the day Will was born, claiming he caught an enormous catfish using his wedding ring as bait. Will has heard his father's fanciful tales many times, and believes they are lies. Fed up by the stories, Will has a falling out with his father. Three years later, Edward is diagnosed with cancer, prompting Will and his pregnant wife Joséphine to spend time with him in Alabama. Edward's life is chronicled through flashbacks, beginning with his boyhood encounter with a witch. She shows Edward how he will die, which does not faze him. As he reaches adulthood, he finds his home too confining, and sets out into the world. He meets a giant named Karl, and they begin traveling together. When they find a fork in the road, they take separate paths. Edward traverses a swamp and discovers the hidden town of Spectre, where he befriends the poet Norther Winslow and the mayor's daughter, Jenny. Not ready to settle down, Edward leaves Spectre, but makes a promise to Jenny that he will return. At Joséphine's request, the bed-ridden Edward tells her how he met his wife, Sandra. In more flashbacks, Edward and Karl visit the Calloway Circus, where Edward falls in love with a beautiful woman. Edward and Karl get jobs in the circus, and the ringmaster Amos Calloway reveals to Edward one detail about the woman each month. Three years later, Edward discovers that Amos is a werewolf, but shows no ill will towards him. In gratitude, Amos reveals the woman's name as Sandra Templeton. Edward confesses his love to Sandra, but she rebuffs him despite his romantic gestures. Sandra's fiancé, Don Price, beats Edward up, which prompts Sandra to break off their engagement and marry Edward instead. In more flashbacks, Edward is conscripted into the army and fights in the Korean War. He parachutes into the middle of a North Korean military show, steals important documents, and persuades the conjoined twins Ping and Jing to help him escape in exchange for making them celebrities. Upon returning home, Edward becomes a traveling salesman. In the present, Will investigates the truth behind his father's tales. He meets an older Jenny, who explains that Edward rescued Spectre from bankruptcy and rebuilt it with help from his circus friends. Jenny reveals that although she loved Edward, he remained loyal to Sandra. Edward has a stroke and Will visits him at the hospital. Unable to speak much, he asks Will to narrate how his life ends. Will tells his father a fantastical tale of their daring escape from the hospital. They arrive at the banks of a lake, where everyone from Edward's stories has gathered to see him off. Will carries his father into the river, where he transforms into a giant catfish and swims away. Satisfied by Will's story, Edward dies peacefully. At the funeral, Will and Joséphine are surprised to see all the people from Edward's stories, although they appear less fantastical. Later, Will passes on Edward's stories to his sons.