Regretfully I locked the door and left the bright fire and bare-walled room where Dorothy had come so near to listening to me. I was disappointed,--of course I was disappointed at my carelessness in losing the man I sought, but--Dorothy’s hand had lain in mine without struggling that last instant of time before Tom came in. There was some balm in Gilead. Yet delays are dangerous, and I felt I must not lose time in following up any advantage gained. As I turned the corner of the stairs, I heard a low exclamation from Dorothy and Tom’s expressive whistle. They were bending over an open door, examining the lock with a match, which Tom held shielded between his palms. As I joined them, Tom pointed without comment at the place where the lock had been. Its bare wood showed lighter surfaces, as the signs had showed the marks of the handiwork of “the man,” and nail holes that told of disappearing metal. “How’s that for a pick lock,” said Tom. “The other one was opened in just the same way. Cragent is the man and I saw him, but couldn’t reach him. What a control he must have over his instrument to be able to destroy a battleship and open the lock of a door by means of disappearing metal.” Dorothy shuddered. “It’s dark here and cold. I want to go back to the hotel,” she said a little tremulously. “I’ll be all right in the morning, and I’ll go with you after ‘the man,’ but now I’m tired--tired.” I think the horror of the thing shadowed us all a bit in that gloomy old London house. The darkness of the corners, the man who had slain so many of his fellow men separated from us by a single partition seemed gruesome and deadening. Those footsteps pacing up and down, did they mean more slaughter, new inventions? Was the mysterious man whom we had sought, the familiar figure Tom had imagined; and dominating thought of all, did Dorothy’s hand rest in mine without struggling that last moment? There was enough to keep my thoughts at work on the way home, even though Dorothy persistently gazed from the window of the four-wheeler and uttered never a word. As we left the carriage, Tom broke silence. “If you feel like it, Jim, I think it wouldn’t be a bad plan to look up Hamerly to-night, and see what he says to all this.” “A good idea,” I said. “I’ll get a hasty bite and run up there. No use in wasting time.” “All right,” said Tom, and Dorothy, as we parted, gave me one shy glance that sent me away in a golden maze of joy and hope. Hamerly was out when I arrived at his lodgings, called away suddenly for a couple of days, the maid reported. On my way back, however, I came to one very definite conclusion. Hamerly must have seen the man face to face in Dr. Heidenmuller’s laboratory. He could settle one vexed question anyway. I was going to find a picture of Regnier if there was one to be had.