The first book of White's saga, The Sword in the Stone, takes as its primary setting the lands governed by Sir Ector, a gruff yet easygoing nobleman. As the story begins, the governess in charge of educating Sir Ector's children—his natural son Kay and his adoptive son Wart (a nickname for Arthur)—has just departed. Sir Ector is mulling a replacement; for their part, Kay and Wart divert themselves by flying a goshawk named Cully around Sir Ector's lands. However, they lose control of the bird; Kay decides to go home, but Wart follows Cully into the fearsome forest that surrounds Sir Ector's estate. It is here that Wart meets two exceptional characters: Sir Pellinore, a discombobulated knight who follows a creature known as the Questing Beast, and Meryln, an eccentric yet formidable wizard who possesses knowledge of future events. Merlyn helps Wart to capture Cully and accompanies Wart back to Sir Ector's castle, where Meryln is taken on as Kay and Wart's new tutor.
As part of Wart's education, Meryln transforms his new pupil into various animals and thus gives Wart exposure to different models of society. Wart observes the various yet somewhat tyrannical lifestyle of fish, the regiment-like arrangements of domesticated hunting hawks, and the belligerent, oppressive, almost totalitarian system followed by ants. He also finds himself among the nonviolent and cooperative geese and meets a self-sufficient, erudite badger. To give Wart a sense of how knights fight, Merlyn transports the boy to see a bout of combat between King Pellinore and another good-natured knight, Sir Grummore. Kay does not accompany Wart on these excursions, but is given a different kind of adventure: Merlyn sends Kay and Wart on a quest that brings them into contact with Robin Hood, takes them to an enchanted castle made of food, and brings Kay face-to-face with a massive griffin, which he triumphantly defeats.
The boys mature, and Merlyn continues to tutor Wart even though the two young men seem destined for different social stations. Kay will become a knight; Wart will serve as his squire. Soon after Kay's knighting, news reaches Sir Ector that the primary ruler of England, King Uther Pendragon, has died. Because Uther has not left an heir, a new ruler must be found—and that ruler will be the man who can successfully remove a sword that is lodged in an anvil atop a stone. Sir Ector, Kay, and a few of their acquaintances set out for London, to enlist Kay in a knights' tournament and to try their luck at the sword in the stone. Wart accompanies them, completely unaware of the requirements regarding Uther's successor. Early in the tournament, Kay forgets his sword and sends Wart to find a replacement; the young squire finds the famed sword in the stone, pulls it out, and returns to Kay. After it becomes apparent that Wart is the only person who can successfully remove the sword, the young man is made the new king. The book ends with Merlyn explaining that Wart was the secret son of Uther Pendragon himself and Merlyn calling Wart by the name by which he will be known henceforth: Arthur.
White's second book, The Queen of Air and Darkness, shifts its focus to the household of Morgause, the wife of King Lot of the Out Isles. The early scenes describe the bleak setting that Morgause and her sons Gawaine, Agravaine, Gaheris, and Gareth inhabit; the sons share strong bonds of family pride and loyalty, but Morgause is a distant mother much of the time. A break from the household's usual habits occurs when three knights—King Pellinore, Sir Grummore, and Sir Palomides—arrive in Morgause's Orkney domain by way of a magic barge. Morgause diverts herself by hunting a unicorn with the visiting knights, while her sons succeed in capturing a unicorn on their own. Eventually, Morgause seems to tire of her visitors. Sir Grummore and Sir Palomides then attempt to divert King Pellinore by disguising themselves in a Questing Beast costume, and their effort lures the Questing Beast herself to Morgause's castle. Fortunately, King Pellinore's love interest, the daughter of the King of Flanders, arrives at the keep and helps to drive the Questing Beast away.
Descriptions of the events centering on Morgause, her family, and her acquaintances are interspersed with descriptions of the young Arthur's endeavors to create a meaningful civic order in England. Arthur is at first exhilarated by kingship and battle, but (with Merlyn's guidance) sees the need to lift England out of a state of brutal warfare and random lawlessness. He thus creates the order of the Round Table to combat the idea that "Might is Right." Nonetheless, Arthur realizes that one last display of might will be necessary to assert his authority. King Lot is after all the leader of an opposition army that outnumbers Arthur's fighting force. To defeat Lot and Lot's allies, Arthur leads an attack by nighttime (to catch Lot off guard) and pursues Lot's knights with the help of the French. Lot returns home in defeat and Morgause ultimately makes her way to Arthur's court, bringing her sons with her and seducing Arthur with the help of a charm called a spancel (a ribbon of human skin). Towards the end of The Queen of Air and Darkness, White explains that Arthur and Morgause are (without being aware of the fact) half-siblings.
The third book in White's saga, The Ill-Made Knight, focuses primarily on the life and adventures of Sir Lancelot. Born and raised in France, Lancelot craves the opportunity to prove himself as a member of Arthur's new order. After three years of the most intensive training possible, Lancelot sets out with his mentor, Uncle Dap, to join the Round Table. The young man fights Arthur (who is armored in black and is unrecognizable) soon after arriving in England. Though Arthur and Lancelot form a close bond, the serious and physically unattractive Lancelot is also drawn to Arthur's wife Guenever, forming with her a spiritual and erotic connection that lasts for much of his adult life.
Lancelot proves his worth to Arthur during a series of quests and tournaments. In particular, he is often credited with aiding and rescuing his fellow knights. As one of his excursions unfolds, he also rescues a girl named Elaine from an enchantment that traps her in boiling water. Lancelot is then seduced by Elaine, who plies him with drink and dupes him into believing that she is Guenever, and impregnates her; she gives birth to a son known as Galahad, who will later become a knight of renown in his own right. When Guenever summons Lancelot and Elaine before her, however, her harsh treatment drives Lancelot to madness. The unhinged knight is eventually found and rehabilitated by Elaine herself, though he leaves her to continue his life of service to Arthur.
While Arthur's court and Lancelot himself gain renown for heroism and civility, a bizarre murder—the slaying of Morgause by her son Agravaine—prompts the knights to re-direct their churning energies and take up holy quests. Prime among these is the Quest for the Grail, a relic which Galahad discovers. The stoic Lancelot is denied access to the Grail; he soldiers on in Arthur's service, even after the suicide of Elaine. On two occasions, Lancelot also successfully defends the honor of Queen Guenever, first against an accusation of poisoning and then against the ill-will of Sir Meliagrance, who stirs up the sensitive subject of Lancelot and Guenever's affair. Despite his transgressions, Lancelot is granted another miracle and heals the wounds of a knight named Sir Urre of Hungary who has come to seek aid in England.
The fourth and final book of the entire narrative, The Candle in the Wind, deals at length with the Orkney faction—which includes Arthur's son by Morgause, the scheming Mordred. Resentful of his father's attempt to kill him during his infancy, Mordred wants to use the fact of Lancelot and Guenever's affair against Arthur, and to his own political advantage. Gawaine strongly opposes the scheme, but Agravaine joins Mordred in an attempt to apprehend Lancelot in Guenever's chamber. Lancelot kills Agravaine, injures Mordred, and escapes. In accordance with Arthur's laws, Guenever is sentenced to be burned at the stake. Lancelot rescues her, yet Gareth and Gaheris are killed in the course of Lancelot's maneuvers; their deaths turn Gawaine against Lancelot.
Together with Gawaine, Arthur journeys into France and lays siege to the castle where Guenever and Lancelot have settled. Guenever is returned to Arthur through an agreement brokered with the aid of the church; however, Gawaine's rage has not abated, and he and Arthur continue their siege of Lancelot's forces. Mordred, meanwhile, has been left in charge of the governance of England itself; he spreads the false news that Arthur and Gawaine are dead in order to take control of the country. Arthur and the grievously wounded Gawaine rush back to England. Lancelot, who is contacted by Gawaine shortly before Gawaine's death, also joins the effort. As Arthur prepares for battle with his half son, he reflects on his possible failings as a leader but finds sources of reassurance: he convinces a page named Thomas Malory to commemorate the Round Table, and achieves insight into how humans could overcome their antagonistic, violent ways. Yet Arthur and Mordred are both fated to be destroyed in the hostilities that follow, even though Arthur's legend will live on.