The Green Knight enters into King Arthur and his knights presence. He challenges the knights to a "game".
"And so all I ask of this court is a Christmas game"(line 63).
Gawain excepts the Green Knights challenge, and chops off the Green Knights head. The Green Knight picks up his head and leaves the room.
“I beseech you, Sire,” he said, “Let this game be mine(lines 118-119).
"Gawain leaves on his quest to find the Green Chapel and fulfill his pledge."
As the end of the year approaches, Gawain, goes out to find the Green Knight, and finds a magnificent castle.
In the castle, Gawain meets a Lord and his wife. The Lord's wife tries to seduce him and also gives him a green belt that makes him invincible.
"I’ll give you merely this sash that’s of slighter value
The Lord and and Gawain exchange what they have received after every day, and Gawain gives him the kisses that he received from the Lord's wife, but he does not give him the girdle.
"When the lord returns at the end of the third day, Gawain gives him a kiss but does not reveal the gift of the sash.
Gawain finds the Green Knight and, the Green Knight only nicks his neck, and The Green Knight reveals he is the Lord. The Green Knight states that Gawain is an honorable knight for completing his task, but he shouldn't have stolen the girdle.
"I consider you polished as white and as perfectly clean As if you had never fallen since first you were born.