Geraint, tributary prince of Devon and one of Arthur's bravest knights, is married to Enid, the only daughter of Yniol. He loves his wife deeply and she responds with equal affection; her only wish is to please him. The queen also loves Enid and is always kind and affectionate to her. In turn, Enid regards Guinevere as the best and most lovely of women. The two ladies are exceptionally good friends.
At this time, the first rumors about Lancelot and Guinevere begin to spread throughout the court, but as yet there is no proof that any romance really exists. Geraint believes the stories and begins to fear that Enid will follow the bad example of her friend, the queen. His worries begin to plague him and he finally asks Arthur's permission to return to Devon. He pretends that his presence is required in order to rule his province better, but his real reason is to take Enid out from under the suspected evil influence of Guinevere.
The king grants Geraint's request and the couple returns to Devon. After they arrive home, Geraint is very affectionate and attentive to his wife. He totally neglects his duties as a ruler and a knight, for he is obsessed with the idea that Enid has left a lover behind at the palace. Made suspicious by his jealousy, he stays at Enid's side at all times:
Forgetful of his promise to the King,
Forgetful of the falcon and the hunt,
Forgetful of the tilt and tournament,
Forgetful of his glory and his name,
Forgetful of his princedom and its cares.
Before long, Geraint's reputation begins to suffer. His people secretly scoff at him and jeer that his manliness is gone. Enid also is upset by his new and disgraceful way of life, but she is afraid to criticize him since she does not want to cause him any pain.
One morning as they lie in bed, she muses out loud about her sad dilemma and berates herself as a bad wife for remaining silent. Geraint awakens and overhears her last few words. He jumps to the conclusion that she is confessing her infidelity and is infuriated. He angrily shouts that he is still a warrior, despite all rumors, and that he will at once go on a quest in order to prove his prowess. She alone is to accompany him, taking no baggage and wearing her oldest and most shabby dress. Enid asks him the cause of his anger, saying, "If Enid errs, let Enid learn her fault." Geraint snaps back, "I charge thee, ask not, but obey." Enid does as she is told, recalling as she dresses the last time she wore these shabby robes.
Many months before, on Whitsuntide (the seventh Sunday after Easter), Arthur had held his court at Caerleon upon Usk. One day all the court had gone hunting, but Guinevere slept late, dreaming of Lancelot. As she and her servants rode alone to join the others, they met Geraint, who was also late, and so they rode together.
Suddenly they encountered a knight, a lady, and a dwarf riding slowly across their path. When Guinevere's maid inquired who they were, the dwarf struck her, and Geraint received the same treatment when he asked the knight's name. After this odd behavior, the three riders continued on their way.
Geraint promised the queen that he would follow these strangers in order to learn their names and avenge this insult to Guinevere's majesty. He would return to the court within three days. Since he was unarmed, he planned to provide himself with weapons somewhere along the way. Guinevere wished him good fortune and expressed the hope that he might meet his bride on this quest. If he did, she promised, no matter who the maiden was, Guinevere would herself dress the girl for her wedding and be a friend to her.
After following the strangers for a while, Geraint came upon a town in a valley. On one side of the town was a large and new fortress into which the strangers rode, and on the other was an old, rundown castle. Geraint found that all the town's inns were full and that everyone was busy preparing for a tournament. He learned also that the proud knight was known as the "sparrow-hawk" and that he could get arms and a place to sleep at the old castle.
At the castle, Geraint met an aged earl, Yniol, his wife, and Enid, their charming and beautiful daughter. They had no servants and were very poor, but they received him kindly and entertained him as best they could.
As his acquaintance with the family developed, Geraint began to fall in love with Enid, and she with him. After a while he explained his mission in the town. Yniol informed him that the strange knight was his nephew, who had robbed him of his earldom and all his wealth. The noble family, however, bore him no real bitterness. Each year, Yniol continued, the scornful and proud "sparrow-hawk" held a tournament. No knight was permitted to enter unless his lady-love were present, and each year the "sparrow-hawk" won the trophy for his paramour.
Geraint borrowed Yniol's rusty old armor and told the family that he would enter the tournament. Enid was to be his lady-love, and if he won he would marry her. The family was delighted, for they knew Geraint's reputation, and Enid was overjoyed to know that her love was answered.
At the tournament Geraint was victorious and Enid was awarded the prize for beauty. The "sparrow-hawk" admitted his real name to Geraint and agreed to ride to Caerleon in order to apologize to Guinevere and return the earldom to Yniol. As it happened, Guinevere was kind to the repentant Edyrn, son of Nudd, and graciously accepted his apology. Being still young, he completely reformed his character and became a true knight. Edyrn eventually died fighting loyally for Arthur in his last battle.
On the third day, Geraint and Enid prepared to return to Caerleon. Remembering the queen's promise, Geraint asked Enid to wear her oldest dress. The maiden was upset by this request, for she feared that her appearance would discredit him at the court. Geraint explained his reason to Enid's mother, and finally Enid complied with her lover's wish.
At Caerleon, Guinevere gladly kept her word, welcomed Enid as a friend, and did her all honor. The queen personally dressed her on the day of her wedding.
Although all this had taken place many months before, Enid had kept this same old dress in which she had first met Geraint as a keepsake. This is the robe she now puts on in obedience to his harsh order.