"Almost childish, is it not?" he said; "yet by means of this simple device The Gables had been emptied of occupant after occupant. There was small chance of the trick being detected, for, as I have said, there was absolutely no aperture from roof to basement by means of which one of them could have escaped into the building." "Then--" "They were admitted into the wall cavities and the rafters, from some cellar underneath, Petrie, to which, after a brief scamper under the floors and over the ceilings, they instinctively returned for the food they were accustomed to receive, and for which, even had it been possible (which it was not), they had no occasion to forage." I, too, stood up; for excitement was growing within me. I took up the piece of silk from the table. "Where did you find this?" I asked, my eyes upon Smith's keen face. "In a sort of wine cellar, Petrie," he replied, "under the stair. There is no cellar proper to The Gables--at least no such cellar appears in the plans." "But--" "But there _is_ one beyond doubt--yes! It must be part of some older building which occupied the site before The Gables was built. One can only surmise that it exists, although such a surmise is a fairly safe one, and the entrance to the subterranean portion of the building is situated beyond doubt in the wine cellar. Of this we have at least two evidences: the finding of the fragment of silk there, and the fact that in one case at least--as I learnt--the light was extinguished in the library unaccountably. This could only have been done in one way: by manipulating the main switch, which is also in the wine cellar." "But, Smith!" I cried, "do you mean that _Fu-Manchu_ ...?" Nayland Smith turned in his promenade of the floor, and stared into my eyes. "I mean that Dr. Fu-Manchu has had a hiding-place under The Gables for an indefinite period!" he replied. "I always suspected that a man of his genius would have a second retreat prepared for him, anticipating the event of the first being discovered. Oh! I don't doubt it! The place probably is extensive, and I am almost certain--though the point has to be confirmed--that there is another entrance from the studio further along the road. We know, now, why our recent searchings in the East End have proved futile; why the house in Museum Street was deserted: he has been lying low in this burrow at Hampstead!" "But the hand, Smith, the luminous hand...." Nayland Smith laughed shortly. "Your superstitious fears overcame you to such an extent, Petrie--and I don't wonder at it; the sight was a ghastly one--that probably you don't remember what occurred when you struck out at that same ghostly hand?" "I seemed to hit something."