King Ban’s son Lancelot is skilled at games, but horribly ugly. Arthur once explained to the young Lancelot his attempt to end the principle of might makes right and asked Lancelot if he wanted to help Arthur do so when he was older. Lancelot said he would indeed like to join Arthur. Fiercely dedicated to Arthur, Lancelot committed himself to a life of training.
Uncle Dap, an expert on all things related to knighthood, trains Lancelot. For three years Lancelot does nothing but learn about knighthood and practice sword fighting and jousting. The narrator says that Lancelot will eventually go on to be the greatest knight in Arthur’s court. Lancelot practices by finding the weak points on armor, lifting weights, and sparring against his brother and cousins in mock swordfights with strict rules.
One day, Merlyn tells Lancelot that Lancelot will be the best knight in the world. He explains that Arthur has married a woman named Guenever and that Arthur already has one hundred knights at his Round Table. Lancelot is disappointed that Arthur has not invited him to join the table. Merlyn appears with his beloved Nimue, and they vanish for a sort of magical honeymoon. Lancelot decides to leave for England immediately.
Uncle Dap accompanies Lancelot as his squire. On their way to Arthur’s castle, in Camelot, they encounter a knight in black armor who challenges Lancelot to a joust. Lancelot defeats the knight, who turns out to be King Arthur. Arthur is thrilled to see Lancelot and knights him back at Camelot. At first, Lancelot is jealous of Guenever because he is fiercely protective of his friendship with Arthur and thinks she is coming between them. Guenever tries to be friendly despite Lancelot’s rejection, but one day he lashes out at her. Once Lancelot sees that he has hurt Guenever’s feelings, he no longer sees her as an evil interloper.
Lancelot and Guenever, now reconciled, begin spending more time together. Uncle Dap and Lancelot argue about Lancelot and Guenever’s relationship, and Lancelot ultimately says that Uncle Dap can remain in Camelot only if he refrains from insinuating anything about Lancelot and Guenever. Arthur is too kind to believe rumors of this relationship, having managed to bury Merlyn’s warning in the back of his mind. To erase his doubt, Arthur decides to bring Lancelot with him to fight the Romans. Lancelot is angry that he is not left behind to guard Guenever, but he goes nonetheless. The war lasts several years—Arthur eventually becomes the overlord of most of Europe, with Lancelot as his new champion and friend.
[H]e had a contradictory nature which was far from holy. . . for one thing, he liked to hurt people.
Lancelot and Arthur return to England determined that nothing can divide them, and they are welcomed with great cheer. When Guenever greets them, however, it becomes clear to Lancelot that she can indeed come between him and Arthur. If he were a less principled man, the narrator says, Lancelot might simply run off with Guenever. Instead, he fights his attraction. But since he cannot stand to be around Guenever when Arthur is around, he decides to leave the court and go on a quest.