After defeating the Irish knight Morholt, Tristan travels to Ireland to bring back the fair Iseult (also appearing under various spellings) for his uncle, King Mark of Cornwall, to marry. Along the way, they ingest a love potion which causes the pair to fall madly in love. In the legend's courtly branch (see below), the potion's effects last a lifetime, but the potion's effects wane after three years in the common branch. In some versions, they ingest the potion accidentally; in others, the potion's maker instructs Iseult to share it with Mark, but she deliberately gives it to Tristan instead. Although Iseult marries Mark, she and Tristan are forced by the spell to seek one another, as lovers. The king's advisors repeatedly endeavour to have the pair tried for adultery, but the couple continually use trickery to preserve their façade of innocence. In Béroul's version, the love potion eventually wears off, and the two lovers are free to make their own choice as to whether to continue their adulterous relationship.