Sir Gawain and the Green Knight

It's Christmas at Camelot and King Arthur won't begin to feast until he has witnessed a marvel of chivalry. A mysterious knight, green from head to toe, rides in and brings the court's wait to an end with an implausible challenge to the Round Table: he will allow any of the knights to strike him once, with a battle-axe no less, on the condition that he is allowed to return the blow a year hence. At the centre of the story of the challenge and its consequences is Arthur's brave favourite, Sir Gawain.