Arthur and his knights travel south after battling the Saxons in Scotland, resting at Castle Carlisle. A woman seeks Arthur to personally rescue her husband from the evil knight of Tarn Wathelyne, who abducts passersby. Arthur takes up the quest, though his men offer themselves instead. The woman leads Arthur to Castle Tarn Wathelyne where Gromer Somer Joure meets and mocks him. In a fury, Arthur charges the knight, but he and his horse are stopped in their tracks by an enchantment, and it is revealed that the castle belongs to Morgana and the woman is one of her servants. Arthur asks for pity and Gromer Somer Joure proposes a quest for Arthur: In one year, Arthur will return to the castle alone with the answer to Gromer Somer Joure’s riddle about what women want most. If Arthur returns with the correct answer, he will be set free, but if he is wrong, he will be slain. Arthur returns to Carlisle with his tale, asking Gawain to help him find the riddle’s answer.

After a year, Gawain and Arthur return to Tarn Wathelyne with books full of answers. Along the way, they come across “the loathliest lady that ever the eye of man rested upon” (219), Lady Ragnell.