I shall never be fool enough to turn knight-errant. For I see quite well that it’s not the fashion now to do as they did in the olden days when they say those famous knights roamed the world.
Don Quixote, Sancho, the priest, the barber, Dorothea, and Cardenio arrive at the same inn where Sancho was tossed in the blanket. The barber takes off his disguise. The innkeeper, his wife, their daughter, and Maritornes join the priest, the barber, Dorothea, and Cardenio to talk about Don Quixote’s madness and the books that have caused it. The priest and the barber want to burn the inn’s collection of chivalric literature, but the innkeeper defends these tales, claiming that the government would not allow them to be published if they were untrue. But he adds that he will never become a knight-errant, because he knows chivalry is out of style. He tells the company that an unnamed man left an old trunk filled with books and manuscripts at the inn. The priest, despite his skepticism about the books of chivalry, asks the innkeeper for permission to copy one of the manuscripts, which the priest reads to the crowd.
The manuscript that the priest reads tells the story of Anselmo and Lothario, two close friends who live in Florence, Italy. Anselmo marries Camilla, a beautiful woman who has the purest intentions. One day Anselmo tells Lothario he wants to test Camilla’s purity and chastity. He asks Lothario to woo Camilla to see whether she will be able to resist. Lothario, in a lengthy speech filled with sonnets and classical references, tells Anselmo that his plan is stupid, but Anselmo does not listen.
Lothario falsely tells Anselmo, on several occasions, that he has tried and failed to woo Camilla. Anselmo spies on the two of them and realizes that Lothario has been lying to him—he has not made any false advances toward Camilla. Anselmo makes Lothario swear that he will try to woo Camilla while Anselmo is away for a week on a business trip. Lothario does try to woo Camilla and inadvertently falls in love with her. Camilla sends a letter to Anselmo begging him to come home and rescue her from his deceitful friend Lothario.
Anselmo receives Camilla’s letter, realizes that his plan is working, and refuses to come home early. Over time Camilla succumbs to Lothario’s advances and they begin a love affair. When Anselmo returns, Lothario tells him that Camilla has resisted his seduction. Anselmo adds to the plan by asking Lothario to write love poetry for Camilla, which the lovestruck Lothario is now thrilled to do. Camilla’s maid, Leonela, helps Lothario and Camilla carry on their affair and takes a lover of her own. Though worried that Leonela will bring her shame, Camilla does not interfere because she fears Leonela will tell Anselmo about her affair with Lothario.
One morning, Lothario sees Leonela’s lover leaving the house and thinks Camilla has taken another lover. In a fit of jealous rage, he tells Anselmo that he has seduced Camilla but that she has not yet acted on her love for him. Lothario reveals Camilla’s plan to meet him in a closet on a certain day and encourages Anselmo to observe his wife’s infidelity. In the meantime, Camilla tells Lothario of her concerns about Leonela, prompting Lothario to realize his mistake. He tells her about his blunder, and she forms a plan to trick Anselmo so that she and Lothario can carry out their affair in the open. She meets Lothario in the closet and, aware that Anselmo is watching, pretends to stab herself rather than give up her purity to Lothario. The deception works, enabling Camilla to carry on her affair with Lothario without Anselmo ever suspecting.
While the priest is reading, Sancho rushes into the room to tell everyone that Don Quixote has slain the giant who captured Dorothea’s kingdom. Rushing to see what has happened, they find that Don Quixote is battling the giant in his sleep and has destroyed several of the innkeeper’s wineskins, which Sancho has mistaken for a giant’s head. When Sancho cannot find the giant’s head, he becomes crazed, fearing that he will not get his governorship.