“I always supposed years ago that the English were the most silent race on earth, but I’m finding out my mistake now. It’s the upper classes that are silent and the country people. Your Londoner can talk a blue streak, once he gets going.” Tom had stepped out into the yard with the agent to give us a further chance to look over the sign, and we were just about to make another examination of the nail holes, when Tom sung out to us, “Come out here, will you?” Out we came, to see the agent hurrying away and Tom, with key in hand, ready to lock up. “I really believe we’ve got something, this time,” he said, in a low voice. “It seems this chap is an understrapper of the agent of the Duke of Moir, who owns all this property about here. He tells me that he let three rooms to a man named Cragent, who occupied them as a workshop or a laboratory off and on for some months, and left about two days ago. Sometimes he’d be gone for months at a time. The man’s gone off for the keys now. He’s going to let us go through the place. He tells me that Cragent probably made some changes, though he hasn’t been inside the place yet.” Tom ended, the agent returned with the keys, and we followed on. Just beyond the mews on the adjoining street, the agent mounted some stairs beside a little bakeshop. The red-whiskered man slipped a key in the lock and threw open the door. Eagerly we pressed in. The bare rooms showed some slight litter left by their former occupant, wrapping paper, broken bits of insulated wire, a shelf which showed behind it heavy disconnected wires which must have led to a motor generator, a sink with high goose neck tap. “It was a laboratory, all right,” I said to Dorothy, who nodded and passed by into the third room. She crossed directly to the rear window. “Look here, Jim,” she called softly. Tom and the agent were left behind in the large centre room. I followed Dorothy’s pointing finger with my eyes, as I reached her side. There, between the buildings, showed a narrow, open strip, which ended in the shadow of a dark arch, crowned by a rudely carved horse’s head. It was the arch where the sign of the “Three Horses” had hung. “If this was the man’s laboratory, his destructive power could have escaped from this window,” murmured Dorothy, “gone straight through, and attacked that sign, without meeting iron anywhere else on the way. Oh, Jim, do you suppose this room corresponded to Dr. Heidenmuller’s wooden room? The man might have wooden panels to the windows and a double door, and taken them down when he left.” I shook my head. “If enough of that deadly stuff got away to destroy the iron of the sign, it would destroy every nail inside the room, and here are iron nails holding the window casing together.” “That’s right,” said Dorothy, as she inspected the nail heads. “Those do look like iron nails.” Then she broke square off. “Got your knife in your pocket, Jim?” Silently I produced and opened it.