I suppose the presence of Eltham and the irritating recollection of his half-confidence were the responsible factors, but my mind persistently dwelt upon the subject of Fu-Manchu and the atrocities which he had committed during his sojourn in England. So actively was my imagination at work that I felt again the menace which so long had hung over me; I felt as though that murderous yellow cloud still cast its shadow upon England. And I found myself longing for the company of Nayland Smith. I cannot state what was the nature of Eltham's reflections, but I can guess; for he was as silent as I. It was with a conscious effort that I shook myself out of this morbidly reflective mood, on finding that we had crossed the common and were come to the abode of my patient. "I shall take a little walk," announced Eltham; "for I gather that you don't expect to be detained long? I shall never be out of sight of the door, of course." "Very well," I replied, and ran up the steps. There were no lights to be seen in any of the windows, which circumstance rather surprised me, as my patient occupied, or had occupied when last I had visited her, a first-floor bedroom in the front of the house. My knocking and ringing produced no response for three or four minutes; then, as I persisted, a scantily clothed and half-awake maid-servant unbarred the door and stared at me stupidly in the moonlight. "Mrs. Hewett requires me?" I asked abruptly. The girl stared more stupidly than ever. "No, sir," she said: "she don't, sir; she's fast asleep!" "But some one 'phoned me!" I insisted, rather irritably, I fear. "Not from here, sir," declared the now wide-eyed girl. "We haven't got a telephone, sir." For a few moments I stood there, staring as foolishly as she; then abruptly I turned and descended the steps. At the gate I stood looking up and down the road. The houses were all in darkness. What could be the meaning of the mysterious summons? I had made no mistake respecting the name of my patient; it had been twice repeated over the telephone; yet that the call had not emanated from Mrs. Hewett's house was now palpably evident. Days had been when I should have regarded the episode as preluding some outrage, but to-night I felt more disposed to ascribe it to a silly practical joke. Eltham walked up briskly. "You're in demand to-night, doctor," he said. "A young person called for you almost directly you had left your house, and, learning where you were gone, followed you." "Indeed!" I said, a trifle incredulously. "There are plenty of other doctors if the case is an urgent one." "She may have thought it would save time as you were actually up and dressed," explained Eltham; "and the house is quite near to here, I understand." I looked at him a little blankly. Was this another effort of the unknown jester? "I have been fooled once," I said. "That 'phone call was a hoax--"