A New Year's feast at King Arthur's court is interrupted by the appearance of a gigantic Green Knight, resplendent on horseback.
He challenges any one of Arthur's men to behead him, provided that if he survives he can return the blow a year later.
Sir Gawain accepts the challenge and decapitates the knight - but the mysterious warrior cheats death and vanishes, bearing his head with him.
The following winter Gawain sets out to find the Knight in the wild Northern lands and to keep his side of the bargain.
One of the great masterpieces of Middle English poetry, Sir Gawain and the Green Knight magically combines elements of fairy tale and heroic sagas with the pageantry, chivalry and courtly love of medieval Romance.