Morgan, feigning sisterly love, has intensified her campaign against Arthur. She has used magic to deceive Lancelot into thinking he has made love to Guinevere; and, disguised as a nun, has told him he must never forget his guilt.

Lancelot lies wounded in a hermit's hut. Guinevere has innocently caused the death of a Knight of the Round Table by giving him a poisoned peach from a bowl, placed there by Morgan and intended to be eaten by Guinevere.

Morgan has told Arthur that Lancelot and Guinevere are lovers and to support her charge has conjured up a vision of them kissing. Lancelot has proved Guinevere's innocence of the murder of Guido by appearing as her champion and defeating Guido's brother in a duel.