Lancelot and Guenever have a few tender moments before Guenever starts to fear that someone will discover them. Just as she is pushing Lancelot toward the door, they see that someone is trying to free the lock. Mordred, Agravaine, and twelve other fully armed knights are waiting outside the door. Lancelot manages to kill Agravaine and steal his sword and armor. He exchanges rings with Guenever and steps outside to face his enemies.
A week later, Gareth, Gawaine, Gaheris, and Mordred are sitting in the Justice Room. Mordred is criticized for running away from Lancelot, who slew all of the other knights outside of Guenever’s chamber. Lancelot has since escaped back to his castle. Guenever has been convicted of adultery and is to be burned at the stake. Everyone expects Lancelot to rescue her. Arthur, at Mordred’s urging, asks Gareth and Gaheris to join the guards who are already posted around her. They go unwillingly, without their armor. Just as Guenever is about to be burned, Lancelot and his knights arrive and rescue her. Arthur and Gawaine are both elated, and Arthur begins to plan out how their parties can be reconciled. Mordred returns from the scene and tells them that Lancelot killed Gareth and Gaheris, even though they were both unarmed. Neither Arthur nor Gawaine believes Mordred at first. Gawaine goes to confirm the news and returns heartbroken after finding Gareth and Gaheris dead.
Six months later, Lancelot and Guenever are in Lancelot’s castle, called Joyous Gard, which is under siege. Lancelot tells Guenever that he does not remember killing Gareth and Gaheris, but that he may well have done so in the confusion. Guenever decides that the only way to save themselves, and Arthur, is to ask the Church to intervene.
The Church agrees to mediate a peace. Back in Camelot, the bishop of Rochester presides over the decision. Lancelot is banished from England, and Guenever returns to Arthur. Gawaine swears, however, that he will still try to get his revenge on Lancelot.
Arthur and Gawaine follow Lancelot to France and place one of his castles under siege. Back in England, Guenever and her maid Agnes are knitting together in her chambers when Mordred enters. He is now quite mad, excessively dandy, and consumed by cruelty. He has founded a new political order, called the Thrashers, who speak of the old Gaelic wars and want to massacre Jews. Mordred tells Guenever that he plans to announce that Arthur and Gawaine have been killed in France and that he is the new king of England. Mordred also tells Guenever that he intends to take her as his wife.
In Arthur’s tent on the battlefield in France, Gawaine is trying to recover from a blow he receives during a fight with Lancelot. It is the second time Lancelot has defeated Gawaine and the second time Lancelot has chosen not to kill him. The bishop of Rochester enters with a letter from Guenever. It tells Arthur about Mordred’s plot. Arthur decides to lift the siege and return to England immediately. Gawaine, who is badly injured, insists on going as well, anxious to wreak revenge on his treacherous brother.