Came a sudden blank, and Dr. Cairn found himself walking again through the narrow street, led by the veiled woman. His impressions were growing dim; and now she seemed less real than hitherto. The streets were phantom streets, built of shadow stuff, and the stairs which presently he found himself ascending, were unsubstantial, and he seemed rather to float upward; until, with the jewelled fingers held fast in his own, he stood in a darkened apartment, and saw before him an open window, knew that he was once more back in the hotel. A dim light dawned in the blackness of the room and the musical voice breathed in his ear: "Your reward shall be easily earned. I did but test you. Strike--and strike truly!" The whisper grew sibilant--serpentine. Dr. Cairn felt the hilt of a dagger thrust into his right hand, and in the dimly-mysterious light looked down at one who lay in a bed close beside him. At sight of the face of the sleeper--the perfectly-chiselled face, with the long black lashes resting on the ivory cheeks--he forgot all else, forgot the place wherein he stood, forgot his beautiful guide, and only remembered that he held a dagger in his hand, and that Antony Ferrara lay there, sleeping! "Strike!" came the whisper again. Dr. Cairn felt a mad exultation boiling up within him. He raised his hand, glanced once more on the face of the sleeper, and nerved himself to plunge the dagger into the heart of this evil thing. A second more, and the dagger would have been buried to the hilt in the sleeper's breast--when there ensued a deafening, an appalling explosion. A wild red light illuminated the room, the building seemed to rock. Close upon that frightful sound followed a cry so piercing that it seemed to ice the blood in Dr. Cairn's veins. "Stop, sir, stop! My God! what are you doing!" A swift blow struck the dagger from his hand and the figure on the bed sprang upright. Swaying dizzily, Dr. Cairn stood there in the darkness, and as the voice of awakened sleepers reached his ears from adjoining rooms, the electric light was switched on, and across the bed, the bed upon which he had thought Antony Ferrara lay, he saw his son, Robert Cairn! No one else was in the room. But on the carpet at his feet lay an ancient dagger, the hilt covered with beautiful and intricate gold and enamel work. Rigid with a mutual horror, these two so strangely met stood staring at one another across the room. Everyone in the hotel, it would appear, had been awakened by the explosion, which, as if by the intervention of God, had stayed the hand of Dr. Cairn--had spared him from a deed impossible to contemplate. There were sounds of running footsteps everywhere; but the origin of the disturbance at that moment had no interest for these two. Robert was the first to break the silence. "Merciful God, sir!" he whispered huskily, "how did you come to be here? What is the matter? Are you ill?" Dr. Cairn extended his hands like one groping in darkness.