The poem opens with a mythological account of Britain’s founding. After the fall of Troy, we are told, various heroes left to build cities. Romulus founded Rome, Ticius founded Tuscany, and Brutus founded Britain. The author introduces Britain’s greatest leader, the legendary King Arthur. This brief introduction ends with the poet telling us he will relate a story he heard told in a hall about a great Arthurian adventure.

The story begins at Christmastime at King Arthur’s court in Camelot. The knights of the Round Table join Arthur in the holiday celebrations, and Queen Guinevere presides in their midst. The lords and ladies of Camelot have been feasting for fifteen days, and now it is New Year’s Day. Everyone participates in New Year’s games, exchanging gifts and kisses. When the evening’s feast is about to be served, Arthur introduces a new game: he refuses to eat his dinner until he has heard a marvelous story.

While the lords and ladies feast, with Arthur’s nephew Gawain and Guinevere sitting together in the place of privilege at the high table, Arthur continues to wait for his marvel. As if in answer to Arthur’s request, an unknown knight suddenly enters the hall on horseback. The gigantic knight has a beautiful face and figure. Every piece of his elaborate costume is green, with flourishes of gold embossing. His huge horse is green, and his green hair and beard are woven together with gold thread. He holds a holly bob in one hand and a huge green and gold axe in the other.

Without introducing himself, the knight demands to see the person in charge. His question meets dead silence—the stunned lords and ladies stare at him silently, waiting for Arthur to respond. Arthur steps forward, inviting the knight to join the feast and tell his tale after he has dismounted from his horse. The knight refuses the invitation, remaining mounted and explaining that he has come to inspect Arthur’s court because he has heard so much about its superior knights. He claims to come in peace, but he demands to be indulged in a game. Arthur assumes the knight refers to some kind of combat and promises him a fight. However, the knight explains that he has no interest in fighting with such young and puny knights. Instead, he wants to play a game in which someone will strike him with his own axe, on the understanding that he gets to return the blow in exactly a year and a day.

The strange conditions of the game shock the court into silence once again. The Green Knight begins to question the reputation of Arthur’s followers, claiming that their failure to respond proves them cowards. Arthur blushes and steps forth defend his court, but just as he begins to swing the giant axe at the unfazed Green Knight, Gawain stands up and requests that he be allowed to take the challenge himself. The king agrees, and Gawain recites the terms of the game to show the Green Knight that he understands the pact he has undertaken. The Green Knight dismounts and bends down toward the ground, exposing his neck. Gawain lifts the axe, and in one stroke he severs the Green Knight’s head. Blood spurts from the wound, and the head rolls around the room, passing by the feet of many of the guests. However, the Green Knight does not fall from his horse. He reaches down, picks up the head, and holds it before him, pointing it toward the high table. The head speaks, reiterating the terms of Gawain’s promise. The Green Knight rides out of the hall, sparks flying from his horse’s hooves. Arthur and Gawain decide to hang the axe above the main dais. They then return to their feast and the continuing festivities.

By framing the central plot of Sir Gawain and the Green Knight with an account of Britain’s founding by the Trojan Brutus, the poet establishes Camelot’s political legitimacy. He also links his own story with classical epics such as Virgil’s Aeneid, thereby creating a literary connection to the ancient world. In the second stanza, the poet claims that he heard the original story of Sir Gawain recited “in hall” (31), but also that it was “linked in measures meetly / By letters tried and true” (that is, it appeared in written format) (35–36). Iin addition to giving his poem both political and literary roots, the poet gives his poem both an oral and a written history, all in two brief stanzas.

The author devotes a lot of space to describing the lavish, intricate details of the feast, including the guests, their clothing, and the hall itself. The knights and ladies of Arthur’s court are full of vitality and joy, resembling the New Year that they celebrate. The poet describes them as “fair folk in their first age,” and he uses words like fresh, lovely, comely, young, and mirthful to describe them (54). Later, the Green Knight echoes these descriptions but exaggerates them, calling Arthur and his knights “beardless children” (280). These descriptions of Arthur’s courtiers as children in their “first age” implicitly compare the court to humankind in its “first age,” before the Fall in the Garden of Eden. The emphasis on the court’s youth and lack of experience suggests that these youthful people might be capable of failure, error, bad judgment, and sinfulness, just as Adam and Eve were.

The poet’s description of Queen Guinevere sitting on her dais, surrounded by exotic tapestries and jewels, suggests that the queen herself is first and foremost a beautiful object. The fact that Guinevere sits surrounded by tapestries from the far reaches of the earth supports the poet’s hyperbolic insistence that Guinevere’s beauty surpasses that of all women in the world. The poet does not touch on the moral or ethical aspects of Guinevere’s character—whether her exceptional body hides an ugly soul or enshrines a pure one remains for the reader to decide. However, any medieval reader would recognize Guinevere’s youthful beauty as the very thing that will later bring about the fall of Camelot: she is destined to betray her husband with Lancelot.

The Green Knight provides a less ambivalent commentary on Arthur and his courtiers by branding them inexperienced children in need of testing. At the same time, the Green Knight’s own character remains ambiguous, so we don’t know whether or not we can trust his judgment. The knight’s green costume and the holly bob he holds in one hand symbolize nature and fertility, but his costume is also ornamented with gold and he carries an axe, symbols of artifice and civilization. The Green Knight represents both the artificial and the natural worlds, and he seems to be a superhuman as well as a supernatural figure. These implications are confirmed when the Green Knight survives decapitation, showing himself to have the power of resurrection.

Gawain’s placement at the high table and his blood ties with Arthur characterize him as someone who maintains a high status among the knights of the Round Table. Yet, when Gawain steps forth to accept the Green Knight’s challenge, he claims he is the weakest of Arthur’s knights. Again, the author refuses to indicate whether Gawain’s self-deprecation stems from a real sense of his own inadequacy or whether it hides a kind of boastful knowledge of his own knightly stature. Many scholars of medieval chivalry believe Gawain’s behavior in this scene accords with the rules of knightly courtesy, but the poem gives us no commentary on Gawain’s motivations at this crucial plot juncture.

Although the Green Knight refers to his agreement with Gawain as a “game,” suggesting that the challenge is no different from any of the other games played by Arthur’s court, the Green Knight words his challenge like a legal contract. He refers to the agreement as a “covenant” and mentions dues, and he makes Gawain repeat the terms multiple times. The Green Knight’s language foreshadows the fact that the his game will have serious ethical implications; it will test not only Gawain’s bravery, but also his honesty and integrity.