But after Tristram had departed, Dagonet and the squires returned, and accusing the shepherds of having set that madman on to assail them, they rode upon the keepers of beasts and beat them shrewdly. Tristram, as it chanced, was not so far off but that he saw this ill-treatment of those who had fed him, and he ran back, pulled Dagonet from the saddle, and gave him a stunning fall to the earth. Then he wrested the sword from his hand and with it smote off the head of one of the squires, while the other fled in terror. Tristram followed him, brandishing the sword wildly, and leaping like a madman as he rushed into the forest.
When Dagonet had recovered from his swoon, he rode to King Mark's court, and there told what had happened to him in the wildwood.
"Let all beware," he said, "how they come near that forest well. For it is haunted by a naked madman, and that fool soused me, King Arthur's fool, and had nearly slain me."
"That must be Sir Matto le Breune," said King Mark, "who lost his wit because Sir Gaheris robbed him of his lady."
Meanwhile, Kehydius had been ordered out of Cornwall by Queen Isolde, who blamed him for all that had happened, and with a dolorous heart he obeyed. By chance he met Palamides, to whom the damsel had reported the sad condition of the insane knight, and for days they sought him together, but in vain.
But at Tintagil a foul scheme was laid by Andred, Tristram's cousin and foe, to gain possession of his estates. This villain got a lady to declare that she had nursed Tristram in a fatal illness, that he had died in her care, and had been buried by her near a forest well; and she further said that before his death he had left a request that King Mark would make Andred king of Lyonesse, of which country Tristram now was lord.
On hearing these tidings, King Mark made a great show of grief, weeping and lamenting as if he had lost his best friend in the world. But when the news came to La Belle Isolde, so deep a weight of woe fell upon her that she nearly went out of her mind. So deeply did she grieve, indeed, that she vowed to destroy herself, declaring bitterly that she would not live if Tristram was dead.
So she secretly got a sword and went with it into her garden, where she forced the hilt into a crevice in a plum-tree so that the naked point stood out breast high. Then she kneeled down and prayed piteously: "Sweet Lord Jesus, have pity on me, for I may not live after the death of Sir Tristram. My first love he was, and he shall be my last."
All this had been seen by King Mark, who had followed her privily, and as she rose and was about to cast herself on the sword he came behind and caught her in his arms. Then he tore the sword from the tree, and bore her away, struggling and moaning, to a strong tower, where he set guards upon her, bidding them to watch her closely. After that she lay long sick, and came nigh to the point of death.
Meanwhile, Tristram ran wildly through the forest, with Dagonet's sword in his hand, till he came to a hermitage, where he lay down and slept. While he slumbered, the hermit, who knew of his madness, stole the sword from him and laid meat beside him. Here he remained ten days, and afterwards departed and returned to the herdsmen.