A fog had descended on London and along the quiet street we were traversing the lights glimmered with the peculiar reddish haze characteristic of such atmospheric conditions. Our footfalls echoed drearily. Even in the heart of a great city there are always sections which seem overlooked and forgotten. Such a street was this. Not even a policeman was in sight. The shop which had attracted Gordon's attention was just in front of us, on the same side of the street. There was no sign over the door, merely some sort of emblem something like a dragon. Light flowed from the open doorway and the small show windows on each side. As it was neither a café nor the entrance to a hotel we found ourselves idly speculating over its reason for being open. Ordinarily, I suppose, neither of us would have given the matter a thought, but our nerves were so keyed up that we found ourselves instinctively suspicious of anything out of the ordinary. Then something occurred which was distinctly out of the ordinary. A very tall, very thin man, considerably stooped, suddenly loomed up out of the fog in front of us, and beyond the shop. I had only a glance of him--an impression of incredible gauntness, of worn, wrinkled garments, a high silk hat drawn close over the brows, a face entirely hidden by a muffler; then he turned aside and entered the shop. A cold wind whispered down the street, twisting the fog into wispy ghosts, but the coldness that came upon me transcended the wind's. "Gordon!" I exclaimed in a fierce, low voice; "my senses are no longer reliable or else Kathulos himself has just gone into that house!" Gordon's eyes blazed. We were now close to the shop, and lengthening his strides into a run he hurled himself into the door, the detective and I close upon his heels. A weird assortment of merchandise met our eyes. Antique weapons covered the walls, and the floor was piled high with curious things. Maori idols shouldered Chinese josses, and suits of mediæval armor bulked darkly against stacks of rare Oriental rugs and Latin-make shawls. The place was an antique shop. Of the figure who had aroused our interest we saw nothing. An old man clad bizarrely in red fez, brocaded jacket and Turkish slippers came from the back of the shop; he was a Levantine of some sort. "You wish something, sirs?" "You keep open rather late," Gordon said abruptly, his eyes traveling swiftly over the shop for some secret hiding-place that might conceal the object of our search. "Yes, sir. My customers number many eccentric professors and students who keep very irregular hours. Often the night boats unload special pieces for me and very often I have customers later than this. I remain open all night, sir." "We are merely looking around," Gordon returned, and in an aside to Hansen: "Go to the back and stop anyone who tries to leave that way."