King Pellinore and his fiancée, Piggy, the daughter of the Queen of Flanders, are sitting on the cliff top in the moonlight. They will soon set off for England to be married. They discuss the names of their future children. They are interrupted by the shouting of Sir Grummore and Sir Palomides, who are trying to convince the Questing Beast to stop her siege of the castle. Pellinore has refused to allow her to be killed.

Merlyn arrives prepared for a walking tour, which will lead to his encounter with Nimue and his imprisonment in the cave for centuries. Sir Grummore and Sir Palomides ask the wizard to do something about the Questing Beast, because she is still in love with her “mate” and waiting for him to come out of the castle. Merlyn suggests that they explain the situation to her, but they doubt that she will listen to them. They ask Merlyn to explain, but he is off to North Humberland to meet with his master Bleise, so that he can write down the details of the battle. He suggests that they psychoanalyze her, asking her about her dreams and explaining the facts of life to her, and then he leaves. Sir Grummore and Sir Palomides take his suggestion, and begin to tell the beast about the birds and the bees.

King Lot and Queen Morgause are in bed in their castle, but the queen is wide awake. She has learned about King Arthur, of his splendor and charm. There is a rumor that he is having an affair with a girl called Lionore, who is the daughter of the Earl of Sanam. The queen opens a coffer and removes a Spancel, which is a long ribbon sliced from a human body. If a woman winds this ribbon around a man as he sleeps and he awakens, the man will die within a year. If he does not wake, he will fall in love with the woman. Queen Morgause takes the Spancel, along with her four children, to the wedding of Piggy and King Pellinore.

The Questing Beast at last decides to switch her affections to Sir Palomides and ends her siege of the castle in time for the wedding party to leave for Carlion. King Pellinore is married to Piggy in the presence of King Arthur. In the north, Merlyn awakens out of a sound sleep, remembering that he forgot to tell Arthur that his mother was Igraine, the mother also of Queen Morgause. In Carlion, Arthur awakens to find Morgause herself standing over him, folding the Spancel. Nine months later, Morgause gives birth to a baby by her half-brother, Arthur. She names him Mordred, and he will be the doom of King Arthur.