then king anguish made haste to return to ireland, taking sir tristram with him. and when he was come there and had told all his adventures, there was great rejoicing over sir tristram, but of none more than of the fair isolt. so when sir tristram had stayed there some while, king anguish reminded him of the boon he should ask and of his own willingness to grant it. "sir king," replied sir tristram, "now will i ask it. grant me your daughter, the fair isolt, that i may take her to cornwall, there to become the wife of my uncle, king mark." then king anguish grieved when he heard sir tristram's request, and said: "far more gladly would i give her to you to wife." "that may not be," replied sir tristram; "my honour forbids." "take her then," said king anguish, "she is yours to wed or to give to your uncle, king mark, as seems good to you."

so a ship was made ready and there entered it the fair isolt and sir tristram, and gouvernail, his squire, and dame bragwaine, who was maid to the princess. but before they sailed, the queen gave in charge to gouvernail and dame bragwaine a phial of wine which king mark and isolt should drink together on their wedding-day; "for," said the queen, "such is the magic virtue of this wine, that, having drunk of it, they may never cease from loving one another."

now it chanced, one day, that sir tristram sat and harped to the fair isolt; and the weather being hot, he became thirsty. then looking round the cabin he beheld a golden flask, curiously shaped and wrought; and laughing, he said to the fair isolt: "see, madam, how my man and your maid care for themselves; for here is the best wine that ever i tasted. i pray you, now, drink to me." so with mirth and laughter, they pledged each other, and thought that never before had they tasted aught so good. but when they had made an end of drinking, there came upon them the might of the magic charm; and never from that day, for good or for ill, might they cease from their love. and so much woe was wrought; for, mindful of his pledge to his uncle, sir tristram brought isolt in all honour into the land of cornwall where she was wedded with pomp and ceremony to king mark, the craven king, who hated his nephew even more than before, because he had returned in safety and made good his promise as became an honourable knight. and from that day he never ceased seeking the death of sir tristram.