Pleure, Weeping Castle
Here Tristram (Tristan), Isoud, Gouvernail, and Bragwaine (Brangain) stopped when Tristram was bringing La Beale Isoud back from Ireland to Cornwall for King Mark. They found that Sir Breunor kept this custom: whenever any knight came by with a lady, they had a beauty contest between the newcomer and Breunor’s own lady. Sir Breunor:
An thy lady be fairer than mine with thy sword smite off my lady's head; and if my lady be fairer than thine, with my sword I must strike off her head.
Afterward the two knights would fight, and whichever won would kill the other and keep the castle and surviving lady. When La Beale Isoud proved the fairer, Tristram took Breunor at his word and, reasoning that the lady was as guilty as her lord, struck off her head. Tristram killed Breunor afterward in the combat.
Malory makes Breunor the father of “Sir Galahad the haut prince,” almost certainly Duke Galeholt of Sorelois, who came with the King of the Hundred Knights to avenge his father’s death, but dropped the project on learning what a custom Breunor had maintained. Presumably Galeholt took the castle and disposed of it as he wished, and the custom almost certainly stopped with Breunor’s death.
There is no reference to any storm that might have blown Tristram off course on his voyage. Therefore, Pluere was probably on the coast of Cornwall or southern Wales. Leaving Ireland from Waterford Harbor would give them less open water to cross, though leaving from Cork Harbor would also have been possible. Wales may be growing overloaded with castles, and I’m not sure I like to put Pluere near Gore and Stranggore. Mark’s country, on the other hand, was likely still a bit more wild and less under Arthur’s influence.