Gawain and the Green Knight

The prince is poor-- in fact, his brother has to pretend to be his squire-- but nonetheless proud. So that when a giant of a green knight enters and causes the king's sword to disappear from the wall, Gawain gamely chops off the knight's head. The knight does not take kindly to this, and requires that Gawain meet him in one year for a return match. Things are never quite what they seem along Gawain's quest, for the green knight takes all sorts of magical forms, including that of his brother. In the end all curses are removed and virtues triumph.