The King Arthur, and Sir Gawain are feasting with all their friends and family. Then the Green Knight barges in and challenges King Arthur one stroke with his axe at his head.
King Arhur hesitates and Sir Gawain steps forward and takes the axe. With one stroke he chops off his head. The green knight did not die, but he picked up head and put it back on. He then challenges Sir Gawain to find him in a year and a day and allow him to do the same.
After he leaves, Sir Gawain is uneasy. Time passes and fall is here. On the Day of All Saints, he prepares for his journey to find the Green Knight. On his journey he fights many beasts along the way. Then he comes upon a castles and the lord and his lady welcome him in.
They make a deal that the host will go hunting everyday and will return in the evening. He was trade his winnings with anything the Sir Gawain could collect that day. He would stay at the castle all day. Each day they make a trade, but within that trade, the lady gives him kisses in exchange for the goods to give the lord.
They continued on the triangle of exchange for some time. Behind the lords back they continue to kiss. Then one day the lady gives him a magical girdle that will protect him from death. Sir Gawain decides to hide it and not give it to the lord. As the day approaches, Sir Gawain thanks them for their hospitality and goes on his way to kind the green knight.
The Green Knight and Sir Gawain meet at last. Sir Gawain offers him his neck for his to fulfill the pact. Sir Gawain flinches on the first blow and the Green Knight makes fun of him and his bravery. Then he hits him again and only draws a little blood on his neck. The Green Knight reveals that he was the lord in the castle and that he is a liar. He forces Sir Gawain to reach his full potential of a knight.