Gawain lies in bed during the early hours of New Year’s morning, listening to the harsh wind wailing outside the castle. Before the sun comes up, he rises and prepares to depart, putting on his armor and ordering servants to saddle his horse. Despite Gawain’s anxiety, his armor shines as brightly as it did when he left Camelot. He does not forget to tie the lady’s girdle around his waist. The girdle’s green color stands out against the red cloth of Gawain’s surcoat.

As Gawain and Gringolet prepare to ride off, Gawain silently blesses the castle, asking Christ to keep it safe from harm and wishing joy on the host and the host’s wife. Accompanied by a guide, Gawain crosses the drawbridge and rides back out into the wilderness, up to the heights of the neighboring snowy hills. There, the guide turns to Gawain and proposes a solution to his impending problem: if Gawain leaves now without facing the knight, the guide promises not to tell anyone. No one survives an encounter with the Green Knight, the guide informs Gawain, so continuing is tantamount to suicide. Gawain thanks the guide for his concern, but he refuses to be a coward. The guide wishes Gawain well and leaves at a breakneck pace, afraid to go any farther into the woods.

Gawain strengthens his resolve and heads onward into the strange forest. He sees no sign of buildings and searches without success for a chapel in the wilderness. Finally he notices a strange mound and investigates it. He spots a kind of crevice or cave, fringed with tall grass, and realizes it must be the Green Chapel.

Suddenly certain that the place belongs to the devil, Gawain curses the chapel and is proceeding toward the cave with his lance in hand when he hears the horrifying sound of a weapon being sharpened on a grindstone. Terrified, and fully aware that the sound means his own doom, Gawain calls out to the lord of the place, stating that he has come to fulfill his agreement. The Green Knight replies, telling Gawain to stay put, and continues to sharpen his weapon. The Green Knight emerges from around a crag, carrying a Danish axe. He welcomes Gawain warmly and compliments him on his punctuality, then tells him he will repay him for his own beheading a year ago. Gawain tries to act unafraid as he bares his neck for the deadly blow.

The Green Knight lifts the axe high and drops it. When the Green Knight sees Gawain flinch he stops his blade, mocking Gawain and questioning his reputation. Gawain tells him he will not flinch again, and the Green Knight lifts the axe a second time. Gawain doesn’t flinch as the axe comes down, and the Green Knight holds the blade again, this time congratulating Gawain’s courage. He then threatens Gawain, saying that the next blow will strike him. Angry, Gawain tells the knight to hurry up and strike, and the knight lifts his axe one last time. He brings it down hard, but causes Gawain no harm other than a slight cut on his neck. Gawain leaps away, draws his sword gleefully, and challenges the Green Knight to a fight, telling him that he has withstood the promised blow. The Green Knight leans on his axe and agrees that Gawain has met the terms of the covenant, but refuses to fight. He points out that he has spared Gawain. He feinted the first two times, in accordance with their contract on the first two days, when Gawain gave him the gifts he had received from the lady. The nick from the third blow was punishment for Gawain’s behavior on the third day, when he failed to tell the truth about the green girdle.

This speech reveals that the Green Knight is the host of the castle where Gawain was staying. He again congratulates Gawain on his bravery, calling him the worthiest of Arthur’s knights and excusing his transgression on the third day. Gawain responds by untying the girdle and cursing it, and asking to regain the host’s trust if possible. The Green Knight laughs and absolves Gawain, now that he has adequately confessed his sin. He gives Gawain the girdle to keep and asks him to come back to the castle and stay there longer to celebrate New Year’s, but Gawain refuses.

Gawain thanks the Green Knight and sends his best wishes to the lady and the old woman, then complains about the deceitfulness of women, who have brought about the downfalls of great men such as Adam, Solomon, Samson, and David. He accepts the girdle, though, and asks that the Green Knight tell him his true name. The knight agrees and reveals himself as Bertilak de Hautdesert, servant of Morgan le Faye, who is the old woman in the castle. Le Faye is also Gawain’s aunt and Arthur’s half sister, as well as Merlin’s mistress; she sometimes helps and sometimes makes trouble for Arthur. Bertilak reveals that Le Faye sent him in disguise as the Green Knight to Camelot in order to scare Queen Guinevere to death. One last time, Bertilak asks Gawain to return with him to the castle and celebrate New Year’s with Morgan le Faye and the others, but Gawain refuses and hurries back toward Camelot.

On his journey back to Arthur’s castle, Gawain’s wound heals, but he continues to wear the green girdle on his right shoulder. When he enters the court, he meets a gleeful reception and tells the story of his encounter with Bertilak. He explains that he intends to wear the green girdle forever as a sign of his failure and sin. Arthur and the court try to comfort Gawain, and they decide that they will all wear belts of green silk as a sign of respect and unity.

The poet concludes by reaffirming the truth of his story, which happened in the days of King Arthur, and which is recorded in “[t]he books of Brutus’ deeds” (2523). In the last wheel of the poem, the poet praises Christ.

Echoing the opening of Part 2, Part 4 opens with a description of the passing of time and a general description of the atmosphere, followed by an account of Gawain putting on his armor and leaving the castle. Though briefer and more somber in tone, this second description balances the earlier one and begins to bring the poem toward its close. The harshness of the winter, with its howling wind and numbing cold, fits Gawain’s bleak mood.

The date on which Gawain sets out to find the Green Chapel is important. In the medieval liturgical calendar, January first marked the Feast of the Circumcision. (In the Judaic tradition, circumcision took place exactly eight days after a child’s birth, so Christ’s circumcision occurred on January 1, eight days after December 25.) The Green Knight’s beheading occurred a year and a day earlier, on the eve of the Feast of the Circumcision, suggesting a parallel between the Green Knight’s head and the foreskin of Christ. That the Green Knight is able to reassemble himself after his decapitation recalls Christian belief in Christ’s resurrection and in the resurrection of all bodies after Judgment Day. On the New Year’s Day a year and a day after the Green Knight’s symbolic circumcision, the Green Knight punishes Gawain not by decapitating him, but by lightly cutting his neck. This cut symbolizes circumcision as well, but it lacks the supernatural elements of the Green Knight’s punishment.

The axe that the Green Knight is sharpening when Gawain finds him is evidence of the knight’s contrast to the courtly tradition from which Gawain comes. At Camelot, the knight’s axe is described at length, and in the forest, we discover that the Green Knight possesses a new Danish axe that replaces the one Gawain and Arthur hung up in the hall at Camelot. The Danish axe connects the Green Knight with England’s Anglo-Saxon roots. Originally associated with the Vikings, the presence of the Danish war axe aligns the Green Knight with a regime that is older than the one Gawain’s lance represents. As such, the Green Knight represents a relationship with a primeval human existence.

When the Green Knight spares Gawain, it is clear that the knight has changed from a character obsessed with the absolute justice of pacts and agreements into one who understands the possibility of compassion and mercy. Up until this part, the Green Knight has seemed to privilege the exact letter of his covenant with Gawain above mercy or even justice. But at the end of the story, he transforms into a much more compassionate figure. He calls it his right to spare Gawain from decapitation, and explains, “You are so fully confessed, your failings made known, / And bear the plain penance at the point of my blade” (2391–2392). The combination of an Old Testament rite, the circumcision, with a New Testament one, the confession, frees Gawain from the sin of lying about the girdle.