Sir Gawain and the Green Knight is one of the late 14th-century books written in Middle English. It is one of the best-known Arthurian stories. Arthurian meaning it relates to the legendary King Arthur of Britain. The story is about Sir Gawain, a knight of King Arthur's Round Table and a nephew of King Arthur, accepting a challenge from a mysterious "Green Knight" who challenges any knight to strike him with his axe if he will take a return blow in a year and a day. Sir Gawain accepts the challenge and beheads the Green Knight. Then the Green Knight stands and picks up his head, and mounts his horse. He then reminds Gawain that the two must meet again at the Green Chapel in a year and a day. The author of this book is unknown.