Part 1
Cervantes, in a metafictional narrative, writes that the first few chapters were taken from "the archives of La Mancha", and the rest were translated from an Arabic text by the Moorish historian Cide Hamete Benengeli.
Alonso Quixano is a hidalgo nearing 50 years of age who lives in a deliberately unspecified region of La Mancha with his niece and housekeeper. While he lives a frugal life, he is full of fantasies about chivalry stemming from his obsession with chivalric romance books. Eventually, his obsession becomes reality when he decides to be a knight errant, donning an old suit of armour. He renames himself "Don Quixote", names his old workhorse "Rocinante", and designates Aldonza Lorenzo (a slaughterhouse worker with a famed hand for salting pork) his lady love, renaming her Dulcinea del Toboso.
As he travels in search of adventure, he arrives at an inn that he believes to be a castle, calls the prostitutes he meets there "ladies", and demands that the innkeeper, whom he takes to be the lord of the castle, dub him a knight. The innkeeper agrees. Quixote starts the night holding vigil at the inn's horse trough, which Quixote imagines to be a chapel. He then becomes involved in a fight with muleteers who try to remove his armour from the horse trough to water their mules. In a pretend ceremony, the innkeeper dubs him a knight to be rid of him and sends him on his way.
Quixote next encounters a servant named Andres who is tied to a tree and being beaten by his master over disputed wages. Quixote orders the master to stop the beating, untie Andres and swear to treat his servant fairly. However, the beating is resumed, and redoubled, as soon as Quixote leaves.
Quixote then chances upon traders from Toledo. He demands that they agree that Dulcinea del Toboso is the most beautiful woman in the world. One of them demands to see her picture so that he can decide for himself. Enraged, Quixote charges at them but his horse stumbles, causing him to fall. One of the traders beats up Quixote, who is left at the side of the road until a neighbouring peasant brings him back home.
While Quixote lies unconscious in his bed, his niece, the housekeeper, the parish curate, and the local barber decide to burn most of his chivalric and other books, seeing them as the root of his madness. However, while filtering through the books, they enter repeated cycles of pity for such good books (which they decide to preserve by themselves), strong determination to get rid of all other books, then back to pity. Eventually, they seal up the library room, later telling Quixote that it was done by a wizard.
Don Quixote asks his neighbour, the poor farm labourer Sancho Panza, to be his squire, promising him a petty governorship. Sancho agrees and they sneak away at dawn. Their adventures together begin with Quixote's attack on some windmills which he believes to be ferocious giants. They next encounter two Benedictine friars and, nearby, an unrelated lady in a carriage. Quixote takes the friars to be enchanters who are holding the lady captive, knocks one of them from his horse, and is challenged by an armed Basque travelling with the company. The combat ends with the lady leaving her carriage and begging him not to harm the Basque.
After a friendly encounter with some goatherds and a less friendly one with some porters driving Galician ponies, Quixote and Sancho enter an inn owned by Juan Palomeque, where a mix-up involving a servant girl's romantic rendezvous with another guest results in a brawl. Quixote explains to Sancho that the inn is enchanted. They decide to leave, but Quixote, following the example of the fictional knights, leaves without paying. Sancho ends up wrapped in a blanket and tossed in the air by several mischievous guests at the inn before he manages to follow.
After further adventures involving a dead body, a barber's basin that Quixote imagines as the legendary helmet of Mambrino, and a group of galley slaves, they wander into the Sierra Morena. There they encounter the dejected and mostly mad Cardenio, who relates his story. Inspired by Cardenio, Quixote decides to imitate what he has read in his chivalric romances and live like a hermit in a display of devotion to Dulcinea. He sends Sancho to deliver a letter to Dulcinea, but instead Sancho finds the barber and priest from his village. They make a plan to trick Quixote into coming home, recruiting Dorotea, a woman they discover in the forest, to pose as the Princess Micomicona, a damsel in distress.
The plan works and Quixote and the group return to the inn, though Quixote is now convinced, thanks to a lie told by Sancho when asked about the letter, that Dulcinea wants to see him. At the inn, several other plots intersect and are resolved. Meanwhile, a sleepwalking Quixote does battle with some wineskins which he takes to be the giant who stole the princess Micomicona's kingdom. An officer of the Santa Hermandad arrives with a warrant for Quixote's arrest for freeing the galley slaves, but the priest begs for the officer to have mercy on account of Quixote's insanity. The officer agrees and Quixote is locked in a cage which he is made to think is an enchantment. He has a learned conversation with a Toledo canon he encounters by chance on the road, in which the canon expresses his scorn for untruthful chivalric books, but Don Quixote defends them. The group stops to eat and lets Quixote out of the cage; he gets into a fight with a goatherd and with a group of pilgrims, who beat him into submission, before he is finally brought home.
The narrator ends the story by saying that he has found manuscripts of Quixote's further adventures.