Arthur orders a joust and asks Guinevere to go with him. She says she is sick, and Launcelot, not yet healed from Mador's strokes, also stays behind. Guinevere points out to Launcelot what gossips will say, and he decides to go after all, but not on the king's side. He lodges with the father of the Fair Maid of Astalot, who falls in love with him and begs him to wear her sleeve as a token of love. Launcelot decides to do so, because he has never worn a lady's token and this will make his disguise complete.
Launcelot and Sir Lavine, brother to the Lady of Astalot, fight brilliantly in the tournament, and only King Arthur knows who Launcelot is. Launcelot wins the field, but is wounded almost mortally. He flees and Lavine helps him to a hermit. Sir Gawain, pursuing the disguised knight he has wounded, discovers that he is Launcelot arid reports the sad news to the queen. When Guinevere hears that Launcelot wore the token of another lady she is furious.
Bors comes to Astalot, tells Launcelot of the queen's wrath and also of a forthcoming tournament where Launcelot can perhaps win back her love; then stays with him while his wounds heal. Earlier than he should, Launcelot gets out of bed, arms himself, and rides to see if he is strong enough to joust. His wounds reopen and he nearly bleeds to death. He is again put to bed, and Bors goes on without him. For all Bors can say, the queen remains furious. Gawain, Bors, and Gareth do better than any other knights — Gareth best of all — but Gareth rides away without stopping for his prize and so forfeits it.
Launcelot meanwhile leaves Astalot, and the lady dies of grief. She asks that her body be placed in a barge and that a letter telling her story be placed in her dead hand. The barge arrives at Camelot, and Guinevere understands the injustice she has done to her lover.