In 16th-century Spain, a 50-year-old country gentleman with a comparatively low income is obsessed with books about knights and chivalry. He decides to become a knight-errant, wandering around the countryside righting wrongs and seeking adventures. He promptly re-names everything associated with himself to make it sound grander. His old worn-out horse becomes Rocinante; the peasant girl he has a crush on becomes Dulcinea of Toboso; and he chooses to call himself Don Quixote.
Quixote leaves his home and allows his horse to choose the road, eventually coming to rest at an inn. He views the inn as a magnificent castle and asks the innkeeper to formally knight him. After Quixote attacks two guests for carelessly tossing around his armor, the innkeeper conducts a quick knighting ceremony to satisfy Quixote and get him to leave the inn.
Next, he encounters a farmer flogging a servant boy, and he orders the man to stop. When the boy says the farmer hasn’t paid him in months, Quixote orders the farmer to pay the wages he has withheld. Then Quixote leaves, assuming the farmer will follow his commands, although the farmer resumes beating the boy.
He encounters a group of merchants and tries to force them to swear that Dulcinea is the prettiest woman in the world. They don’t respond positively, and he is about to attack them when his horse trips and he falls to the ground. One of the merchants’ mule drivers beats him. Quixote is so badly beaten that he cannot walk. A neighboring farmer carries him home. Quixote’s friends, niece and housekeeper are anxiously waiting for his return. His friends burn all his books about chivalry, but to no avail. He wakes up and seeks out adventures again.
Quixote asks a poor farmer named Sancho Panza to become his squire. The two of them set out on the road and almost immediately encounter a large group of windmills. Quixote says the windmills are giants and decides to attack them. One windmill knocks him down and breaks his lance, causing him to believe an enchanter turned the giants into windmills.
Quixote sees two friars on the road, riding ahead of a lady’s carriage. He attacks, mistaking them for evil enchanters capturing a princess. The friars escape, but half of Quixote’s ear is cut off in a battle with the lady’s servant.
After a fight with some pony drivers, Quixote and Sancho are badly beaten with rods and manage to safely reach an inn. Due to several cases of mistaken identity, Quixote is beaten up by the innkeeper’s servant girl’s lover, as is Sancho, and they ride away from the inn in worse shape than they arrived. Quixote says the inn is under an evil enchantment.
Quixote frees slaves who are being sent to the Spanish galley for their crimes, but he also gets into a fight with them after he frees them. They throw stones at Quixote and Sancho and steal their meager belongings. They then meet a nearly insane young man named Cardenio, who was betrayed by his friend Don Fernando. Fernando married Cardenio’s beloved Lucinda against her will.
Quixote’s best friends in La Mancha, a priest and a barber, resolve to bring him back home to La Mancha so he can recover from his madness. They happen to meet a wronged maiden named Dorotea, who has been wooed and then abandoned by Don Fernando. They convince Dorotea to say that she is a princess and to beg Quixote to come back with her to defeat the giant who has invaded her kingdom. Dorotea, the priest, the barber, Sancho, Quixote and Cardenio all end up at the previous inn, the place that is supposedly under an evil enchantment. Don Fernando and Lucinda also arrive at the inn, and after several tear-filled speeches, the two main couples are sorted correctly: Cardenio ends up with Lucinda, and Don Fernando is again with Dorotea.
Some officers of the Holy Brotherhood, the police force of the area, come to the inn with a warrant for Quixote’s arrest, because he freed the galley slaves who were supposed to serve in the Spanish fleet. The priest talks them out of arresting Quixote, then the priest and barber proceed to tie up Quixote and put him into a cage on the back of an ox cart so they can carry him home to his niece and housekeeper. The women are distressed at Quixote’s unhealthy and dazed appearance, and they fear that he will set out upon more adventures. This concludes the first part of Don Quixote.
The second part of Don Quixote was published 10 years after the first one, and the author mentions an unauthorized sequel that a different author published in the interim. He opens part two with a scathing letter condemning the other author for stealing his characters.
The priest and barber go to see Quixote one month after his previous journeys have concluded. Sancho also visits and gets into an argument with Quixote’s housekeeper, who thinks it is Sancho who led Quixote on their knightly misadventures, instead of the other way around.
Sancho tells Quixote that a book has been written about their previous adventures, so the two of them are now well known. From this point forward, most of the people that Sancho and Quixote meet have read Don Quixote part one, or have read the false sequel by another author, so Quixote and Sancho become characters twice over — characters in the novel itself and characters in their own reality. People treat the duo differently based on what they have read about them.
Sancho brings a young scholar named Sanson Carrasco to meet Quixote. Sanson has read Don Quixote part one and describes it further to them. Sanson is fond of tricks and mischief, and when he talks with the priest and barber about helping Quixote prepare to leave home on a second adventure, it becomes clear that all three men are so amused by Quixote’s antics, they don’t really want him to recover from his madness.
As they start their second journey, Quixote and Sancho meet a cart full of actors dressed in costumes to look like heroes, gods and demons. One actor’s intentionally wild antics scare Rocinante and make Sancho’s donkey run away. Sancho talks Quixote out of attacking the actors, since the actors are armed with stones and would overpower the duo.
Quixote and Sancho run across another knight errant in the woods, and they overhear him singing a sad song about his lady love. Quixote decides to have further conversation with the knight, and they eventually decide to duel each other. The other knight wears shiny armor, so he is referred to as the Knight of Mirrors. Quixote knocks the Knight of Mirrors to the ground. When the knight’s visor is removed, he discovers it is Sanson Carrasco, from their hometown. Quixote sends Sanson away, battered but alive.
The duo encounters a wagon carrying two lions that are intended to be a present for the King of Spain. Quixote demands that the driver stop and unlock the cages so that he can battle the lions. The first lion decides not to come out of its cage, and for once Quixote follows Sancho’s advice and doesn’t provoke the lion to fight him. The lion incident ends without a battle, and Quixote even pays the driver money for frightening and inconveniencing him.
They travel to the famous Cave of Montesinos, and Quixote asks Sancho and the guide to lower him into the cave by ropes. When they pull him up, he seems to be asleep. When he wakes up, he tells them a fantastic story. He says in the cave he met the legendary Montesinos, a character famous in old Spanish ballads, and entered a crystal palace. He saw the body of Durandarte, an equally legendary knight, and was told that Merlin the enchanter was keeping Montesinos and Durandarte under a spell that only Quixote could release. His story is so convincing that Sancho almost believes it.
They meet a beautiful duchess in the woods, and she and her husband, a duke, invite Quixote and Sancho to their castle. The duke and duchess have read the first book of Don Quixote, so they like him but are inclined to amuse themselves by tricking him and making fun of his madness. For example, they know that Quixote is under the belief that his beloved Dulcinea of Toboso (who never appears in the novel) is under an enchantment, which has turned her into a peasant girl. The duke and duchess arrange for someone to dress up as the enchanter Merlin and tell Quixote that Dulcinea’s enchantment can be reversed if Sancho strikes his own backside with a whip 3,300 times. Sancho finds this unreasonable and refuses to help disenchant Dulcinea in this fashion.
The next falsehood the duke and duchess concoct is the plight of Countess Trifaldi. One of their servants dresses as a distinguished countess and tells Quixote that a princess and a knight she once served have been turned into figurines by an evil giant. She tells Quixote that he has to ride on a flying wooden horse to a faraway land to fight the giant.
Quixote and Sancho are blindfolded and put on a wooden horse with servants blowing air from a bellows to make them feel as if they’re flying through the air to a distant location. The horse explodes from the fireworks inside it, throwing both men to the ground. When they come to their senses, they find a note saying that they have undone the enchantment just by attempting to undo it.
The duke and duchess make Sancho the governor of a small town, which they tell him is an island, since he has always wanted to govern an island. Quixote gives him some excellent advice about how to rule wisely. Even though the whole thing is intended as a practical joke, Sancho actually rules well, judges cases fairly and creates good laws. The governorship comes to an end when Sancho’s people stage an enemy attack at the behest of the duke and duchess. Since Sancho doesn’t feel brave enough to defend his people from enemies that he does not realize are imaginary, he decides to forfeit his governorship.
Quixote and Sancho are reunited and finally leave the duke and duchess’s castle. After several more adventures, Quixote meets someone called the Knight of the White Moon, who challenges him to combat. The Knight of the White Moon says that if he wins the challenge, he wants Quixote to go home and give up knight errantry for a year. Quixote is knocked off of his horse and accepts the one-year banishment to his hometown. One of Quixote’s friends follows the knight and discovers that it was again Sanson Carrasco, dressing as a knight, trying to get Quixote to give up his madness and go home.
Quixote reacts badly to his loss of the duel. He’s not severely injured by the fall, but he stays sick in bed for six days from the emotional upset of defeat. The duo journeys slowly toward La Mancha. Quixote and Sancho are captured by armed men who force them to march back to the duke and duchess’s castle yet again.
At the castle, they are holding a funeral for the servant girl Altisidora, who supposedly died from her unrequited love for Quixote. A man dressed as a judge says that she will come to life again if Sancho is slapped 24 times across the face. Sancho reluctantly accepts the assault, and Altisidora revives.
At last the duo returns to La Mancha, with Quixote plagued by doubts that he’ll ever see Dulcinea again. When he reaches his home, his housekeeper and niece are thrilled, and he tells the priest and Sanson that he intends to be a shepherd for a year. He has picked special shepherd names for himself and his friends, suggesting they all become shepherds together. But he never manages to fulfill his new shepherding dream. In his weakened physical and emotional state, he succumbs to a fever and dies, surrounded by loving friends. Before his death, he renounces chivalry and knight errantry as foolish, and asks to be called by his real name, Alonso Quixano.