Alonso Quixano, a middle-aged country gentleman, obsessively consumes tales of chivalric adventure to the point where he starts to see their fantastical contents as reality, and determines to reinvent himself as a heroic knight under the name ‘Don Quixote de La Mancha’. Donning an antique suit of armour he rides out into the countryside on a worn-out old nag encountering various people, all of whom marvel at his unique madness, and most of whom he either assaults or is assaulted by as the result of his attempts to act out chivalric scenes. Having been 'knighted' by a local innkeeper, who is desperate to placate his increasingly violent guest, he is ultimately recognised and recaptured by an acquaintance from his village.
Despite the best efforts of Quixote's friends and relatives, who purge his collection of books and seal the door to his library, he escapes more of a knight than ever, having taken as a squire the trusting farmer Sancho Panza, to whom he promises governorship over a portion of the great kingdom he believes will soon be his. They undergo many ordeals in pursuit of Quixote’s delusional ideals, which lead variously to his famous tilt at a windmill, an attack on a funeral procession, and the successful liberation of a group of criminals from their royal guard. Having thus fallen afoul of the law the pair seek refuge in a nearby mountain-range, where Quixote honours his noble lady ‘Dulcinea el Toboso’ (in reality a peasant-girl called Aldonza he has never actually met) by imitating the lovesick madness of Amadis, his premiere chivalric role-model. Parallel with the knight's delusional adventures a real-life romance of fantastical proportions is resolved when two divided couples, Cardenio and Lucinda, and Ferdinand and Dorothea, are improbably reunited at a nearby inn. The lovers aid a priest and barber from Quixote's village in convincing him that he is enchanted, allowing them to return him home once more.
In the second part, Quixote's delusions receive unexpected validation when a published account of his adventures (the one we have been reading) is brought to his attention, supposedly the work of Arabic chronicler Cide Hamete Benengeli. For the rest of the book he is beset not only by imaginary enemies he alone can see, but by all too real ones who manipulate his now infamous condition for their own ends. He is engaged in combat by the mysterious 'Knight of Mirrors' who, once defeated, reveals himself as Sansón Carrasco (BA) - a student friend of the hidalgo who has reasoned that besting the Don in a chivalric duel might bring his deranged fantasy life to an end. Quixote and Sancho later encounter an eccentric Duke and Duchess, also readers of the chivalric romance novels, who use their apparently endless wealth to weave around the pair a web of simulated adventures and intricate deceptions for their own amusement. They even grant Sancho his longed-for governorship for a short time during which he fulfils the role with surprising competence, before being violently deposed in a mock invasion.
Having escaped the cruel torments of the duchal couple Quixote and Sancho journey to Barcelona only to encounter Sansón Carrasco once more, now styled as the 'Knight of the White Moon', who exacts his vengeance on the hidalgo. Quixote, finally disgraced in his own eyes as well as those of others, accepts his opponent's command and returns to his village where, as his much-abused body succumbs to mortal illness, his mind is suddenly freed from its madness. 'Alonso Quixano' once more he sincerely renounces the books which have brought him to his fate, going so far as to stipulate in his will that, should his niece marry any man who has even heard of chivalric romances, she will be cut off without a penny. At Quixano's death his narrator Cide Hamete Benengeli echoes the sentiment, concluding by way of an assertion that with him will die the absurd romances it has been the book's purpose to ridicule and discredit.