A Green Knight came to the kingdom of King Arthur declaring a challenge of blows. "'And I will stand for your stroke, steady on the floor, / Provided you honor my right, when my inning comes, / To repay. / But let the respite be / A twelvemonth and a day'" (lines 76-80).
A year and one day later, the Green Knight sought the opponent of his challenge. At first, none stepped forward. King Arthur himself then accepted the challenge, but his nephew Gawain persuaded him to allow himself to take his place. "'I beseech you, Sire,' he said, / 'Let this game be mine'" (lines 123-124). He did this to earn honor. A year and a day later, he would accept the Green Knight's blow at the Green Chapel.
Gawain and the Green Knight agreed to trade defenseless blows upon each other. The Green Knight knelt down and prepared himself to accept the first blow. Gawain raised the Knight's ax and struck down onto his bare neck. "The fair head fell from the neck to the floor of the hall" (line 158). The rest of the Knight's body picked up the head and left the castle on its green steed. All of the nobles rejoiced.
Close to a year and a day later, Gawain set out to find the Green Chapel. He came upon a castle of a lord and lady who offered to house him. There was only one catch. "While the lord is out hunting, the lady attempts to seduce Gawain. Gawain resists her, however, and on the first two days accepts only kisses, which he gives to the lord at the end of each day in exchange for what the lord has gained in the hunt" (text in bold page 216).
On the third day at his host's castle, the lady gave Gawain a green, silk sash that she claimed to be of high value. She said, "'For the man who goes to battle in this green lace, / As long as he keeps it looped around him, / No man under Heaven can hurt him, whoever may try'" (lines 232-234). Gawain accepted this gift, the first one he had, and did not give it to the lord at the end of the day. He then set out to find the Green Knight with the sash.
He found him sharpening his ax in a rugged place. He knelt and flinched at the first blow. The next was a feint. The third swing nicked him in the neck drawing a spurt of blood. The Green Knight told Gawain that he was the lord from the castle and that he had asked his wife to flirt and give him the sash as a test. Since he only kept it to save his life, the Knight only nicked him. The Knight said, "'I consider you polished as white and as perfectly clean / As if you had never fallen since you were born'" (lines 385-386). Gawain then returned to Camelot safely.