On the day of the Pentecost feast, when all the Round Table is assembled and Arthur, according to his custom, is waiting for some marvel to be revealed before he begins his meal, Sir Gawain announces the arrival of three men and a dwarf. One of the men, who at first seems unable to walk, then proves perfectly whole and agile, is "the goodlyest yonge man and the fayreste" the court has ever seen. He asks three gifts. For now he will name only the first: food and drink for a year.
Sir Kay scorns the young man as a "vylayne borne," on the grounds that "as he is, so he hath asked," and he mockingly calls him "Beaumains," that is, "pretty hands." Kay says he'll make the boy work in the kitchen. Gawain and Launcelot defend the boy, but Kay is obstinate and the boy goes with him willingly. Gawain had reason to be kind to Beaumains, Malory says, "for that proffer com of his bloode, for he was nere kyn to hym than he wyste of"; Launcelot's kindness, on the other hand, "was of his grete jantylnesse and curtesy."
The following Pentecost, a damsel named Lynet arrives at court to ask help for her sister, whose castle is under siege by the Red Knight of the Red Lands. She will not tell her sister's name, so Arthur refuses to send any of his knights with her. Now Beaumains asks the remaining two gifts: that he be assigned this adventure and that he be knighted by Launcelot. Arthur agrees.
Lynet is furious when she sees a kitchen boy assigned to her, but she has no choice. Beaumains' dwarf produces a splendidly dressed horse and fine armor, to all the court's amazement, and Beaumains rides off without spear or shield. Kay follows to mock him and Beaumains takes Kay's spear and shield. Beamains tells Launcelot, who has seen all this, that he is Gawain's brother Gareth.
He is knighted and, bearing Kay's shield, begins a series of adventures each more difficult than the last, throughout which Lynet belittles and scorns him. He beats six thieves, two knights at a bridge, the Black Knight, the Green Knight, Sir Persaunt of Inde, and at last the Red Knight of the Red Lands. Lynet finally comes to approve him.
Now Lyonesse requires that he serve her faithfully for a year in order to win her love. He does so, and in further encounters proves his might, pluck, and chastity. He and Lyonesse plan a tournament at which Gareth is to win her as his lady. After the tournament, but before Gareth rejoins Lyonesse, he fights the Brown Knight without Pity (Bereuse Saunz Pit) and — unknowingly — his own brother Gawain. Lyonesse stops the final battle by making the two brothers known to each other; then Gareth and Lyonesse are married at Arthur's court.
The tale of Gareth, besides being long, is one of the most complex in all Le Morte d'Arthur, both in plot and in its organization of textural and structural details. It will be possible here to suggest only its general place in the total tragedy. The tale brings together themes from the two preceding tales, "Arthur and King Lucius," and "Launcelot du Lake." As Launcelot kills Tarquin, so Gareth kills Bereuse. As Launcelot wears Kay's shield and armor, thus appearing to work for virtue's sake, not for personal glory, Gareth, using the same shield, does indeed work for virtue's sake — only Kay and Launcelot ever know of the shield.
His humble entry as a seeming cripple, his year in the kitchen, his meek toleration of Lynet's abuse, and his year of service to Lyonesse all suggest his humility. More perfectly than any other knight, Gareth lives by both the letter and the spirit of the Pentecostal oath established by Arthur at the end of "Tor and Pellanor." He is the embodiment of mercy, renouncing even the avenging justice — blood payment — most closely associated throughout the Morte d'Arthur with his brother Gawain. For all his love of Gawain, Gareth will not defend murder or vengeance even when Gawain is guilty of them. Seeing that Gawain is "evir vengeable," Gareth shuns him, seeking out Launcelot instead.
Gareth is also the ideal lover, contrasting with both his close friends, Launcelot and Tristram, whose love, for all its virtuous loyalty, is adulterous. The true end of love, Gareth's story shows, is marriage. And all the symbolic extensions of the ideal of marriage which Malory had earlier set up in "Arthur and King Lucius" are reintroduced here.
Gareth's tale ends in his own marriage and that of his brothers, followed by the related ritual of feudal commendation, wherein all those who have been overcome or rescued by Gareth come to pledge their fealty in return for his protection as overlord; the ending then widens out to Arthur's parallel dispersing of titles and lands.
In the tale of Gareth, Malory presents the high point in the rise and fall of Arthur's kingdom. Almost every motif here has its analog in "Arthur and King Lucius," but whereas that tale concerns a noble kingdom at war, Gareth's tale concerns a kingdom in time of peace. Every element in the tale reflects the elegance, the ritualistic pomp and circumstance of a peacetime kingdom: the knights Gareth fights are all identified with clear, bold colors — black, green, red, india-blue, red again, and brown — and great tournaments formally divide the main action. It should be added, incidentally, that the tale (Malory's clearest departure from any known source) introduces one of his most brilliant creations of character — the sharp-tongued Lynet.