I turned without a word, slipped into my dressing-gown, and with Platts passed aft along the deserted deck. The sea was as calm as a great lake. Ahead, on the port bow, an angry flambeau burnt redly beneath the peaceful vault of the heavens. Platts nodded absently in the direction of the weird flames. "Stromboli," he said; "we shall be nearly through the Straits by breakfast-time." We mounted the narrow stair to the Marconi deck. At the table sat Platts' assistant with the Marconi attachment upon his head--an apparatus which always set me thinking of the electric chair. "Have you got it?" demanded my companion as we entered the room. "It's still coming through," replied the other without moving, "but in the same jerky fashion. Every time I get it, it seems to have gone back to the beginning--just _Dr. Petrie_--_Dr. Petrie_." He began to listen again for the elusive message. I turned to Platts. "Where is it being sent from?" I asked. Platts shook his head. "That's the mystery," he declared. "Look!"--he pointed to the table; "according to the Marconi chart, there's a Messageries boat due west between us and Marseilles, and the homeward-bound P. & O. which we passed this morning must be getting on that way also, by now. The _Isis_ is somewhere ahead, but I've spoken all these, and the message comes from none of them." "Then it may come from Messina." "It doesn't come from Messina," replied the man at the table, beginning to write rapidly. Platts stepped forward and bent over the message which the other was writing. "Here it is!" he cried excitedly; "we're getting it." Stepping in turn to the table, I leant over between the two and read these words as the operator wrote them down: _Dr. Petrie_--_my shadow_.... I drew a quick breath and gripped Platt's shoulder harshly. His assistant began fingering the instrument with irritation. "Lost it again!" he muttered. "This message...." I began. But again the pencil was travelling over the paper:--_lies upon you all_ ... _end of message_. The operator stood up and unclasped the receivers from his ears. There, high above the sleeping ship's company, with the blue carpet of the Mediterranean stretched indefinitely about us, we three stood looking at one another. By virtue of a miracle of modern science, some one, divided from me by mile upon mile of boundless ocean, had spoken--and had been heard. "Is there no means of learning," I said, "from whence this message emanated?" Platts shook his head, perplexedly. "They gave no code word," he said. "God knows who they were. It's a strange business and a strange message. Have you any sort of idea, Dr. Petrie, respecting the identity of the sender?" I stared him hard in the face; an idea had mechanically entered my mind, but one of which I did not choose to speak, since it was opposed to human possibility.