Sir Mordred and the Green Knight — Phyllis Ann Karr

From the start, this Yuletide had been overshadowed by dread. After the last New Year's Day, in Camelot, would Sir Mordred return to keep his word? And would the Green Knight find them again in Caerleon? How could he fail? The annual progressions of King Arthur's Court were less than no public secret: its own members, and all the other people of England, must be able to find it at need.