The poem opens with the short mythological view of the British history. This way the author places the plot of the poem in the certain period of time and praises the King Arthur by mentioning his name among other famous characters. The actual story begins afterwards, representing the true account the author has heard about "in town."

All the Knights of the Round Table have gathered in order to celebrate the New Year. They enjoy the great feast, play games and have fun. Sir Gawain, the king Arthur's nephew and King Arthur's wife, Guinevere are sitting near the king. After the dinner has been served, the king Arthur introduces a game. He rejects to eat until someone amuses him with a marvelous story. As if he is being heard, a knight runs into their castle, head to toe green, caring a green birch in one hand and a huge axe in another, requiring to meet the lord of the castle. While the rest of the court is bewildered by the presence of the unearthly figure, King Arthur remains collected. He presents himself and kindly ask the Green Knight to join their feast. The Knight refuses by saying that he has come to inspect the court he has heard about and to be a part of the game. Although the Green Knights claims that he comes in peace ("You may be sure by this branch that I bear here that I pass in peace and seek no quarrel") his presence is intimidating and radiates with violence. It seems that his overall figure represent raw power, wilderness found only with animals. Green color and the holy branch in has stand for the connection with nature, while axe in his hand represents the power. To support this theory, throughout the poem the reader will certainly notice that the author dedicated many stanzas to detailed description of the Green Knight (disguised as the lord of the castle) enjoying the turmoil during the hunt and bloodshed he made in the woods. In favor of such theory, the description of the Green Chapel is the most natural place of all in the entire poem, untouched by the human hand.

Although the author never speaks of the emotions of characters, it is easy to read between the lines and notice that the Green Knight brought to King's Arthur court marvel as well as fear.

The King Arthur seems to be the only one who notice threatening tone in the knight's voice and promises him a fight if that's the reason of his visit, but the knight does not hesitate to humiliate the king as well as his court by saying that no one is fit to fight with him as they are all "beardless children," targeting their youth and lack of life experience, which will turn out to be true throughout the poem, when Sir Gawain falls for the lord's wife not realizing that he is being fooled.

Instead of starting a fight, the Green Knight offers a strange proposal- he seeks a knight that will strike him with his own axe. If the knight won, he would get the axe as a trophy. If the Green Knight won, the knight would have to look for him exactly a year and a one day later for payback. The court is even more bewildered by this proposal and everyone seems to be reassessing their common sense. King Arthur applies for this feat, but Sir Gawain steps in and voluntarily takes the Green Knight's axe, claiming that he is the least important on the court and therefore the best fit to die in this duel. The Green Knight exposes his neck and Sir Gawain decapitate him with one blow. The head rolls over the floor, and the courtiers push it further with their legs until the body of the Green Knight stands up as if nothing happened and goes over to get his head. Caring a head in his hands, he opens his eyes and recite the conditions they have set upon the agreement and then rushes through the door. The happy bunch in the court continue their feast, while King Arthur and Sir Gawain display the axe in a visible place so that everyone can marvel about it. The author finishes the first part with lines:

"Now take care, Sir Gawain, that thou blench not

for the pain to prosecute this adventure

that thou has taken on hand,"

as if trying to bring Sir Gawain to his senses and make him realize that this was not a joke so there is nothing to laugh about.

The second part jumps into the days before the payback. After rich description of the season change, the author focuses on Sir Gawain. It seems that the thrill of the decapitation has passed giving way to the anxiety over the upcoming troubles. On a Day of All Saints, King Arthur makes a feast in honor of Sir Gawain who is about to leave the court the next morning in quest for the Green Knight. When the moment comes, the ceremonial preparations begin. A carpet from Toulouse is stretched over the floor and then his best clothes and arms are brought. All of these are described in great details, but the most important piece is the shield with the pentangle on it and Virgin Mary's face inside of it. As the author states himself:

"It is a sign that Solomon set formerly as a token of truth,

by its own right, for it is a figure that holds five points,

and each line overlaps and locks in another;

and throughout it is endless;

and the English call it everywhere,

as I hear, the endless knot.

Therefore it suits this knight and his clear arms,

forever faithful in five things,

and in each of them five ways."

This is highly symbolical and deserves deeper analysis. The pentangle represents all the virtues a knight should have- generosity, fellowship, chastity, courtesy, and charity. Besides, it symbolizes skillfulness of his five fingers, the perfection of his five senses, his devotion to the five wounds of Christ, his reflection on the five joys of Mary in Christ. Intertwining Christianity with the great warrior should result in sinless knight and these markings are there to remind him of it.

Ready for the quest, Sir Gawain bestrides his horse Gringolet and heads off to the Wales and Northwest England, determined to find the Green Knight. Time passes by with no results. Weary of the search, weather and all kinds of trouble, he prays to find a shelter on a Christmas day so that he can hear mass. Not much time has passed by before his prayers are heard. He finds a castle in the distance and heads towards its light. Everyone in the castle is kind to him, the lord has choses the best clothes and chamber to sleep in. The description of the lord of the castle resemble to the description of the Green Knight- they are both old but in a good shape, sturdy in figure and strong. Moreover, the lord proposes a game to Sir Gawain, just as the Green Knight did back at the Camelot. Although lord's game does not include decapitation, it depicts the competing spirit they share. The author obviously had an intention of giving a hint. Back in the castle, Sir Gawain is a kind of a celebrity, admired by everyone. He is introduced to two ladies, one which is young and beautiful and the other old and ugly. Not much is said about them, only we know is that the young one is the lord's wife. The game the lord has proposed, to exchange daily the acquired gifts has been approved by Sir Gawain.

The third part starts with the first day of the lord's hunt in the woods. Many stanzas are devoted to gruesome details of animal hunt and murder in which the lord seem to enjoy more than anyone else. On the other hand, Sir Gawain sleeps pampered in his comfort bed. The parallel between these two men is obvious in the Third part. The narrator alternately jumps from the bloodshed in the woods to the warm surroundings of the castle where Sir Gawain sleeps carefree. This highlights the difference not only between these two characters, but sets the border between nature, wilderness and strength on the one side and men, civilization and meekness on the other.

On the first day of hunt, while the lord is away, his wife sneaks into Sir Gawain's bed and tries to seduce him. Sir Gawain is flattered by her attention but puts her off anyway. She manages to give him one kiss before leaving his chamber. At the end of the day, the lord brings a deer and handles the venison to Sir Gawain as a prize, while Sir Gawain shares a kiss with the lord as his own prize. The second day, the lord brings home a wild boar, while Sir Gawain shares two kisses. On the third day, the lord's wife goes further into the seduction by asking Sir Gawain to give her love tokens. He refuses to give or take any love tokens with her, until she mentions the green girdle with magic powers that protect the person who carries it from the death of any kind. Sir Gawain cannot resist this offer as the first thing that comes to his mind is the upcoming reencounter with the Green Knight that will seal his destiny. He takes a girdle and after the lord has come from the hunt and given him a fox skin, Gawain shares three kisses, not mentioning the girdle.

It's not by an accident that these three animals are present in the story. Each of them symbolizes a stage of Sir Gawain's moral downfall. The deer represents innocence of Sir Gawain at the beginning of the "affair." He is young, naive and susceptible to sin. The wild boar's feisty nature represents Gawain's effort to resist the lord's wife. The fox is a symbol of cunningness, so in a way it represents deceit both from the lady who is a part of the entire hoax, as well as from Gawain who decides not to mention the green girdle he got beside three kisses.

The fourth part is the most important because it reveals the truth about each character. It begins with Sir Gawain's departure from the lord's castle in pursue of the Green Knight. One of the servants accompany him until the middle of the woods and refuses to go any further out fearing for his life. He gives Sir Gawain friendly advice and promises to keep it a secret if he decides so, to take another road and goes home without looking for the Green Knight. Sir Gawain rejects this offer and goes further alone until he spots a cave overgrown with bushes wondering whether this could be the Green Chapel. The sound of the grindstone confirms his doubt and soon he faces the Green Knight. The Green Knight takes two blows to feign, and at the third one he manages to only make a small cut on his neck. These three blows represent the payback for the game they played three days. The first two blows were for those two days when he shared the kisses he got from the lady, and the third one was for not being completely honest and keeping the green girdle a secret. However, the Green Knight finds him reputable knight of all and forgives him the mistake. Before saying good bye Sir Gawain wants to know Green Knight's true identity and he comes clean about it by revealing the entire truth. His name is Bernlak de Hautdesert, and he is sent by Morgen la Fay, the old lady in the castle who knows all about the magic, to inspect King Arthur's court and make Guinevere die out of fear. The old lady is actually King Arthur's half-sister, therefore Sir Gawain's aunt.

The poem ends where it has started- at the Camelot. Sir Gawain has returned home safe and sound, with the green girdle on his right arm, but doubtful about his morality. He shares his story with King Arthur and courtiers, believing the cut on his neck to be the forever mark of the blame and mistake he made. In order to show him respect, Knights of the Round Table decided to wear oblique green band as sign of respect towards Sir Gawain. At the end of the day, the entire poem is about the chivalry and by carrying the green band for the hero's sake the Knights of the Round Table show how close they are. The green color that once represented a danger in Sir Gawain's life, has not only saved him from death (the green girdle), but has become a color that will become a reminder of his brave venture.