Book 20 Summary

Agravaine, brother of Gawain, and Mordred, the illegitimate son of Arthur and his half-sister Margawse, hate both the queen and Launcelot and plot to shame them. They appeal to the courage of the knights of the court pointing out that as knights, they should be ashamed to let sin against King Arthur go on under their own noses. Gawaine reprimands them, reminding them of all the times Launcelot has saved and helped them, but Agravaine goes to the king with his accusation anyway.

Arthur does not want to admit that such a thing is possible, because Launcelot had done so much for he and the queen and he loved Launcelot. Agravaine encourages the king to set a trap, which he does, saying that he will be away overnight hunting.

Agravaine and Mordred take twelve knights (all from Scotland) to watch the queen's chambers...