At that time, there was a young knight at the Irish court called Tristan, who was there as a messenger from his uncle, King Mark of Cornwall, to ask for the hand of the beautiful Iseult for his King. The young man did not hold out much hope of accomplishing his mission, for the King of Cornwall was advanced in years, and he doubted that the beautiful princess would consider him a good match. On hearing the royal declaration, Tristan thought that if he could kill the dragon the maiden would be his and he could take her to King Mark.

Knowing that water was fatal for fire dragons, Tristan took a wine skin full of water and hung it over the door to the monster's lair. Then he lay in wait for the dragon to come out. So fierce was the dragon and so many deaths had he caused that not even the most valiant knight in the kingdom dared challenge him. However, the major-domo of the royal household, who nursed a secret passion for the princess Iseult, was hiding near the cave, watching to see what would happen. The crafty steward had no intention of killing the beast, he was much too afraid, but he was certain that by using his wits, he would be able to take advantage of the exploits of some brave knight and receive the credit for killing the dragon himself.

From his hiding place, the astonished major-domo saw an unknown youth present himself before the monster's cave and call him in a loud voice. When the dragon appeared, the wine skin full of water fell on him and quenched his fire. Then, a fierce struggle began between the knight and the dragon. At last, after long hours of gruelling combat, Tristan managed to kill the monster, but was so exhausted that he only had the strength to cut out and keep the dragon's tongue before losing consciousness.

At the sight of the slain dragon and the senseless knight lying on the ground, the treacherous steward decided to turn the situation to his advantage. With one stroke he cut off the monster's head and presented himself to the king as the author of the deed, claiming the promised reward. Iseult was in great despair, for she did not desire the old major-domo for a husband. She could not believe that the steward had succeeded in such a difficult task, and the princess paid a secret visit to the dragon's cave.

When she reached it and saw the unconscious young man, Iseult understood that they had been tricked. She liked the knight's handsome features and, as she did not know of Tristan's plans, she sent her servants to bring back the wounded man in secret to the palace, where she tenderly cared for him. Two days later, the court gathered to announce officially that the dragon had been slain and to give the triumphant major-domo the princess's hand. Proud as a peacock the steward of the royal household stood at the foot of the throne waiting for his reward.

Iseult, dressed in gold and silver sat next to the King, and the room was thronged with countless courtiers decked out in their finery. The King had not yet spoken when Tristan burst into the room and asked for the hand of the princess. 'By what right do you ask for her and?' asked the King, furiously. 'By the right of my sword and as the slayer of the dragon, Your Majesty', replied the young man.

The court burst out laughing, but the fury of the Irish lord was evident. 'You presumptuous young man, perhaps you are unaware that the major-domo has killed the monster?' Then the beautiful princess broke in, for she could not help thinking that the unknown knight was much handsomer and that his kisses would be much sweeter than those of the steward. 'Let him explain, father, I implore you.' 'Very well,' agreed the King, 'let the stranger speak.'

'Let the dragon's tongue speak for me', retorted Tristan. 'The dragon is dead, you impudent young man, how can he speak?' 'Look in his mouth, your Majesty', replied the hero. The steward was thrown into confusion when they opened the monster's mouth and saw that his tongue was missing. 'Here is the missing tongue', and Tristan showed the astonished courtiers and the smiling Iseult the tongue of the animal which he had kept.

And so the major-domo's trick was discovered, and he was severely punished for his treason. The King declared Tristan the winner and then Tristan announced that he did not claim the princess's hand for himself, but for his uncle, Mark of Cornwall. The monarch was delighted at the news, for the King of Cornwall was rich and much appreciated by the Irish court. As for Iseult, she did not allow herself to be too disappointed by this announcement, for she had decided to win the heart of the valiant knight.

The legend tells how Tristan also fell in love with the beautiful princess, and this love led to a sad tale in which the two lovers ended up dying, unable to part.