Arthur's men discover Cornwall has sent a seven-headed monster, a sprite named Burlow Beanie, to spy on them.
Sir Bredbeddle, the Green Knight, wages a long battle against him with a sword from Cologne, a Milanese knife, a Danish axe, and finally a sacred page from the Christian Bible gives him the upper hand.
A missing section likely described Arthur's men taking possession of Cornwall's other magical objects and learning the secret of their use from the sprite.
Making chivalric vows is a central theme in the medieval English tale The Avowing of Arthur, while the importance of keeping one's pledges is important to tales like Sir Gawain and the Green Knight and The Wedding of Sir Gawain and Dame Ragnelle.
In other stories, Cornwall is ruled by either Arthur's cousin Cador, or by King Mark, the uncle of Tristan and husband of Iseult.