Mad or sane, there was but one thought still in John Huish's brain, and that was to get this fiend, this haunting demon, by the throat. Whether he was human or some strange creature from another world, he had ceased now to speculate; his head had been troubled with too much stress. All he felt was that they two could not exist together upon earth: that was his evil half, and he must kill it. Once or twice a thrill of mad rage made his nerves tingle, for he seemed to see Gertrude resting lovingly in that other's arms, responding to his caresses, smiling in his face, and blessing him with her love; and at such moments his brain whirled like one of the wheels by his side. The sight of the cab in front drove these thoughts away, though, and, clenching his teeth, he shook his head as if to clear his brain for the one object in view. And now, for the first time, he became aware of a strange pain, and of something warm trickling down beside his ear, and putting up his hand, he withdrew it covered with blood. "He could not kill me," he muttered, taking out his handkerchief and applying it to where the bullet had struck the top of his head and glanced off, making a deep cut which bled freely. He did not know it then, but it was the one thing for which he had reason to thank the man he pursued. Though sent with a mission to destroy, it was the saving of his life. On still through the crowded streets, which were empty to John Huish, for he saw nothing but the cab before him. As in his then wild state there seemed to be room in the world for but one of them two, so in his vision there was room but for the single object he pursued. There were turnings and checks, and more than once the cab was nearly lost; but the driver he had knew his work, and twice over, when Huish was about to leap out and continue the pursuit on foot, there was the cab on ahead. Over a bridge, and then down a turning for a short cut. Yes, he must be making for Waterloo Station; and as Huish sprang out he saw the man he sought at the ticket-office, and darted towards him. The fugitive looked round in the act of taking his ticket, saw the wild face of Huish, and turned and fled, with his pursuer hunting him like a dog and close upon his heels. Without a moment's hesitation, on reaching the platform, he ran to the right, doubled back along the next, leaped down on the line, crossed it, reached the next platform, doubled again in and out, amidst the shouts of the porters, passed through a tangle of trains and empty carriages, and so reached again another platform, before glancing back to find Huish doggedly on his track.