In the summer of 1605 he received a summons to London to appear before the courts, in answer to a claim of compensation for their father's death made by the children of Nicolas Slanning. He set out attended by a single servant. He was a prey to terrors, particularly afraid of his father-in-law, Sir William Courtenay, who he knew was very incensed with him because of his behaviour to his wife, the daughter of Sir William. He had moreover been squandering money which had been settled on her by deed. Every day his fancies got more disordered, till he put up at Kingston-on-Thames, his last resting-place before reaching London; but there, a prey to alarms and fancies, he would not lie, and rode on to Twickenham, where he stopped at "The Anchor," a small hostelry kept by one Daniel Alley, whom he roused out of his bed about 2 a.m. The host, to accommodate him, was forced to surrender to him his own bed, and send his wife to sleep with the children. But the knight could not rest after he had lain down, and was heard crying out that he was pursued by enemies. Very early, the host rose that he might go out and mow a field, but his wife entreated him not to leave the house. He laughed at her alarms, but she persisted, and a neighbour who was going to help in the mowing came in. Sir John Fitz started out of sleep on hearing voices, and persuaded that his fears were verified, rushed from his room in his nightgown, with his sword, and ran Alley through the body. He then wounded the unhappy wife, and finding the error into which he had fallen, finally mortally wounded himself. A doctor was sent for, but he tore off the bandages, and so died, lamented of none save Lusty Jack.