After the victory over Rome, Launcelot leaves for adventures and is accompanied by his nephew Sir Lyonel. On the road, Lancelot feels sleepy and so stops to rest under an apple tree. While he sleeps, Lyonel sees three knights pursued by a fourth. The pursuer quickly defeats the three knights with his spear and ties them to their horses. Lyonel fights the attacker but is also defeated and bound. The knight, Sir Tarquine, then takes them all to his castle.
Elsewhere, Sir Ector de Marys has gone to join Lancelot but before he does he meets a forester who sends him to Sir Tarquine’s castle to find adventure. Sir Ector fights Sir Tarquine, loses, and is thrown into the dungeon with Sir Lyonel and the others.
While Launcelot sleeps, four queens, one of them Morgan le Fay, Queen of Gore, accompanied by four knights approach and kidnap him while he sleeps, then take him to le Fay’s Castle Charyot. With her companions, Queens of North Galys, Estelonde, and the Outer Isles, she demands that he abandon his love of Gwynevere and take one of them as his paramour. Instead, Launcelot agrees to fight for her father, King Bagdemagus, against the King of North Galys (one of the Queen’s is fighting her husband?) and three knights of the round table (he’s to fight fellow knights?). Her demands are a little unclear.
Lancelot heads off to the abbey where he will fight. Lost, he stops at a red silk pavilion to sleep. In the middle of the night Sir Belleus, who is the actual owner, returns and goes to bed. He mistakes Lancelot for his paramour and they start kissing (lol). A fight ensues once they realise their mistake and Lancelot wounds the knight but then tends to his wounds as apology. Lancelot sends him to be made a knight by Arthur.
Lancelot arrives at King Bagdemagus’s castle. The next day, Launcelot helps Bagdemagus fight King Galys and his forces including the three knights: Sir Modred, Sir Madore de la Porte, and Sir Gahalantyne. They are defeated and Launcelot is rewarded by Bagdemagus.
Lancelot returns to the apple tree, where he fell asleep at the start of the story, and encounters a noblewoman on a white palfrey. She says knights are harassing her and several other noblewomen. She wants Launcelot to first rescue the knights imprisoned by Sir Tarquine (and Launcelot’s original companion Lyonel) and then return with them to protect her and the others. Lancelot encounters Tarquine who accuses Launcelot of killing his brother, Sir Calaros of the Dolorous Tower, and demands that they fight. They do, and Launcelot beheads him. The castle treasure is given to the prisoners: Sir Brandelis, Sir Galyhuddis, Sir Kay, Sir Alydukis, Sir Marhaus, etc.
Launcelot leaves with the noblewoman to then defeat the knights that have been harassing her; Sir Ector and Sir Kay follow to fight alongside. They defeats the harassing knights. The noblewoman asks Launcelot why he is not married and Gwynevere comes up: “I believe that a true knight is neither adulterous nor lecherous.”
Launcelot moves on. He kills a porter blocking him from crossing a bridge. He kills two giants from the same castle as the porter. The castle is that of Tintigil, who’s widow Uther married and begat Arthur (see the Merlin section in The Tale of King Arthur). He stays and one night sees Sir Kay attacked by three enemies. Launcelot defeats them and the next morning he leaves in Sir Kay’s armor. In it, he encounters enemies of Sir Kay, whom he defeats, and fellow knights who perceive the ruse.
He then follows a ratchet to a castle upon a green marsh where a woman grieves her dead husband Sir Gylberd the Bastard. Launcelot rides through the forest and meets a woman whose brother, Sir Melyot, was wounded by Sir Gylberd. The brother can only be healed by a piece of Gylberd’s bloody shroud and sword which can be found in Chapel Perelous. He goes to the Chapel and passes 30 knights with distorted faces, upside down shields, and in black armor. As he’s leaving, the sorceress Lady Hallews of the Castle Nygurmous asks him for a kiss. He denies her because he loves Gwynevere and she dies of a broken heart two weeks later. Sir Melyot is cured and invited to Camelot.
Another lady, the wife of Sir Phelot, ruled by the King of North Galys, must retrieve an escaped falcon or her husband will kill her. Sir Phelot appears and Launcelot realizes that the lady was used to trap him. He kill Sir Phelot.
Sir Launcelot stops a husband, Sir Pedivere, from beheading his wife. She is innocently in love with her cousin, but he doesn’t trust her. They travel together and when Launcelot is not watching, Sir Pedivere beheads his wife. Launcelot forces him to carry her body to the Pope for burial then go to Gwenivere and beg for mercy.
Launcelot finally returns to Camelot and is greeted by many knights who praise his recent exploits.