So then they sailed till by fortune they came nigh a castle that hight Pluere, and thereby arrived for to repose them, weening to them to have had good harbourage. But anon as Sir Tristram was within the castle they were taken prisoners; for the custom of the castle was such; who that rode by that castle and brought any lady, he must needs fight with the lord, that hight Breunor. And if it were so that Breunor won the field, then should the knight stranger and his lady be put to death, what that ever they were; and if it were so that the strange knight won the field of Sir Breunor, then should he die and his lady both. This custom was used many winters, for it was called the Castle Pluere, that is to say the Weeping Castle.
How Sir Tristram and Isoud were in prison, and how he fought for her beauty, and smote off another lady’s head.