Book XV. tells how Parzival met with a mighty heathen, with whom

he fought fiercely, and how he was well-nigh vanquished. How he found the heathen to be his brother, Feirefis Angevin, and how the twain rode together to the court of King Arthur.

Of the welcome given to Feirefis by King Arthur and his knights; of his riches; and of the kings conquered by the two brothers.

How a feast of the Round Table was holden, and how Kondrie bare tidings of Parzival's election to the Grail Kingdom, and summoned him, his wife, and his son Lohengrin, to Monsalväsch; and how Parzival and Feirefis rode thither with Kondrie as their guide.