The meanwhile Morgan le Fay thought that King Arthur was slain, and that she might now be queen of the land, with Sir Accolon as King. Then came tidings unto her that Accolon was dead and King Arthur had his sword again. When Queen Morgan wist all this she was so sorrowful that near her heart brake, but because she would not it were known, outward she kept her countenance, and made no semblance of sorrow. But well she wist, if she remained till her brother Arthur came thither, there should no gold go for her life. Then she went unto Queen Guenever, and asked her leave to ride into the country.
"Ye may abide," said Queen Guenever, "till your brother the King come home."
"I may not," said Morgan le Fay, "for I have such hasty tidings that I may not tarry."
"Well," said Guenever, "ye may depart when ye will."
So early on the morn, ere it was day, she took her horse and rode all that day and most part of the night, and on the morn by noon she came to the abbey of nuns where lay King Arthur. Knowing he was there, she asked where he was at that time; and they answered how he had laid him in his bed to sleep, for he had had but little rest these three nights.
Then she alighted off her horse, and thought for to steal away Excalibur his sword. So she went straight unto his chamber, and no man durst disobey her commandment. There she found Arthur asleep in his bed, and Excalibur in his right hand naked. When she saw that, she was passing heavy that she might not come by the sword without awaking him, and that she wist well would be her death. Then she took the scabbard, and went her way on horseback.
When the King a woke and missed his scabbard, he was wroth, and he asked who had been there. They said his sister Queen Morgan had been there, and had put the scabbard under her mantle, and was gone.
"Alas," said Arthur, "falsely have ye watched me."
"Sir," said they all, "we durst not disobey your sister's commandment."
"Ah," said the King, "let fetch the best horse that may be found, and bid Sir Ontzlake arm him in all haste, and take another good horse and ride with me."
So anon the King and Ontzlake were well armed, and rode after this lady; and so they came by a cross, and asked a cowherd if there came any lady late riding that way.
"Sir," said the poor man, "right late came a lady riding with forty horses, and to yonder forest she rode."
Then they spurred their horses and followed fast. Within a while Arthur had a sight of Morgan le Fay, and he chased as fast as he might. When she espied him following her, she rode a greater pace through the forest till she came to a plain. She saw she might not escape, wherefore she rode unto a lake thereby, and said, "Whatsoever becometh of me, my brother shall not have this scabbard." And then she let throw the scabbard in the deepest of the water, where it sank anon, for it was heavy of gold and precious stones.
Thereupon Queen Morgan rode into a valley where many great stones were, and when she saw that she must be overtaken, she shaped herself, horse and man, by enchantment, unto great marble stones. Anon came Sir Arthur and Sir Ontzlake, but they might not know the lady from her men, nor one knight from another.
"Ah," said the King, "here may ye see the vengeance of God, and now I am sorry that this misadventure is befallen."
And then he looked for the scabbard, but it could not be found, so he returned to the abbey where he came from. When Arthur was gone, Queen Morgan turned all into the likeness as she and they were before, and said, "Sirs, now may we go where we will."
So she departed into the country of Gore, and there was she richly received, and made her castles and towns passing strong, for always she feared much King Arthur.
When the King had well rested him at the abbey, he rode unto Camelot, and found his Queen and his barons right glad of his coming. And when they heard of his strange adventures as is afore rehearsed, they all had marvel of the falsehood of Morgan le Fay, and many knights wished her burned because of her wicked enchantments. "Well," said the King, "I shall so be avenged on her, if I live, that all Christendom shall speak of it."
On the morn there came a damsel from Morgan to the King, and she brought with her the richest mantle that ever was seen in that court, for it was set as full of precious stones as one might stand by another, and there were the richest stones that ever the King saw. And the damsel said, "Your sister sendeth you this mantle, and desireth that ye should take this gift of her, and in what thing she hath offended you, she will amend it at your own pleasure."