A pair of lovers who predate the stories of King Arthur but nonetheless appear in the Vulgate and Post-Vulgate Cycles. Sir Tristan was a knight who brought Iseult the Fair back to Cornwall to marry his uncle King Mark after killing Morholt, an Irish knight extorting the king. During the return journey, the pair ingest a powerful potion and fall deeply in love with each other, but Iseult nevertheless marries Tristan's uncle. The love potion, however, forces the pair to continuously seek one another out, and King Mark eventually discovers their affair. Tristan escapes his execution and later marries a different woman known as Iseult of the White Hands. Their story inspired Richard Wagner's opera Tristan und Isolde.