Gulliver's Travels is an adventure story (in reality, a misadventure story) involving several voyages of Lemuel Gulliver, a ship's surgeon, who, because of a series of mishaps en route to recognized ports, ends up, instead, on several unknown islands living with people and animals of unusual sizes, behaviors, and philosophies, but who, after each adventure, is somehow able to return to his home in England where he recovers from these unusual experiences and then sets out again on a new voyage.
Book I: When the ship Gulliver is traveling on is destroyed in a storm, Gulliver ends up on the island of Lilliput, where he awakes to find that he has been captured by Lilliputians, very small people — approximately six inches in height. Gulliver is treated with compassion and concern. In turn, he helps them solve some of their problems, especially their conflict with their enemy, Blefuscu, an island across the bay from them. Gulliver falls from favor, however, because he refuses to support the Emperor's desire to enslave the Blefuscudians and because he "makes water" to put out a palace fire. Gulliver flees to Blefuscu, where he converts a large war ship to his own use and sets sail from Blefuscu eventually to be rescued at sea by an English merchant ship and returned to his home in England.
Book II: As he travels as a ship's surgeon, Gulliver and a small crew are sent to find water on an island. Instead they encounter a land of giants. As the crew flees, Gulliver is left behind and captured. Gulliver's captor, a farmer, takes him to the farmer's home where Gulliver is treated kindly, but, of course, curiously. The farmer assigns his daughter, Glumdalclitch, to be Gulliver's keeper, and she cares for Gulliver with great compassion. The farmer takes Gulliver on tour across the countryside, displaying him to onlookers. Eventually, the farmer sells Gulliver to the Queen. At court, Gulliver meets the King, and the two spend many sessions discussing the customs and behaviors of Gulliver's country. In many cases, the King is shocked and chagrined by the selfishness and pettiness that he hears Gulliver describe. Gulliver, on the other hand, defends England.
One day, on the beach, as Gulliver looks longingly at the sea from his box (portable room), he is snatched up by an eagle and eventually dropped into the sea. A passing ship spots the floating chest and rescues Gulliver, eventually returning him to England and his family.
Book III: Gulliver is on a ship bound for the Levant. After arriving, Gulliver is assigned captain of a sloop to visit nearby islands and establish trade. On this trip, pirates attack the sloop and place Gulliver in a small boat to fend for himself. While drifting at sea, Gulliver discovers a Flying Island. While on the Flying Island, called Laputa, Gulliver meets several inhabitants, including the King. All are preoccupied with things associated with mathematics and music. In addition, astronomers use the laws of magnetism to move the island up, down, forward, backward, and sideways, thus controlling the island's movements in relation to the island below (Balnibarbi). While in this land, Gulliver visits Balnibarbi, the island of Glubbdubdrib, and Luggnagg. Gulliver finally arrives in Japan where he meets the Japanese emperor. From there, he goes to Amsterdam and eventually home to England.
Book IV: While Gulliver is captain of a merchant ship bound for Barbados and the Leeward Islands, several of his crew become ill and die on the voyage. Gulliver hires several replacement sailors in Barbados. These replacements turn out to be pirates who convince the other crew members to mutiny. As a result, Gulliver is deposited on a "strand" (an island) to fend for himself. Almost immediately, he is discovered by a herd of ugly, despicable human-like creatures who are called, he later learns, Yahoos. They attack him by climbing trees and defecating on him. He is saved from this disgrace by the appearance of a horse, identified, he later learns, by the name Houyhnhnm. The grey horse (a Houyhnhnm) takes Gulliver to his home, where he is introduced to the grey's mare (wife), a colt and a foal (children), and a sorrel nag (the servant). Gulliver also sees that the Yahoos are kept in pens away from the house. It becomes immediately clear that, except for Gulliver's clothing, he and the Yahoos are the same animal. From this point on, Gulliver and his master (the grey) begin a series of discussions about the evolution of Yahoos, about topics, concepts, and behaviors related to the Yahoo society, which Gulliver represents, and about the society of the Houyhnhnms.
Despite his favored treatment in the grey steed's home, the kingdom's Assembly determines that Gulliver is a Yahoo and must either live with the uncivilized Yahoos or return to his own world. With great sadness, Gulliver takes his leave of the Houyhnhnms. He builds a canoe and sails to a nearby island where he is eventually found hiding by a crew from a Portuguese ship. The ship's captain returns Gulliver to Lisbon, where he lives in the captain's home. Gulliver is so repelled by the sight and smell of these "civilized Yahoos" that he can't stand to be around them. Eventually, however, Gulliver agrees to return to his family in England. Upon his arrival, he is repelled by his Yahoo family, so he buys two horses and spends most of his days caring for and conversing with the horses in the stable in order to be as far away from his Yahoo family as possible.