Presently I was shown up to that bare and shining room which I remembered having visited in the past. I stood just within the doorway, smiling. Inspector Dunbar rose, as the constable went out, and stood looking across at me. I had counted on striking him dumb with astonishment. He was Scottishly unmoved. "Well," he said, coming forward with outstretched hand, "I'm glad to see you. I knew you would have come to us sooner or later!" I felt that my eyes sparkled. There was no resentment within my heart. I rejoiced. "Look," he continued, taking a slip of paper from his note-book. "This is a copy of a note I left with Dr. Stuart some time ago. Read it." I did so, and this is what I read: "_A:_ the name of the man who cut out the lid of the cardboard box and sealed it in the envelope--Gaston Max! "_B:_ the name of the missing cabman--Gaston Max! "_C:_ the name of the man who rang me up at Dr. Stuart's and told me that Gaston Max was dead--Gaston Max!" I returned the slip to Inspector Dunbar. I bowed. "It is a pleasure and a privilege to work with you, Inspector," I said .... This statement is nearly concluded. The whole of the evening I spent in the room of the Assistant Commissioner discussing the matters herein set forth and comparing notes with Inspector Dunbar. One important thing I learned: that I had abandoned my nightly watches too early. For one morning just before dawn someone who was _not_ Zara had paid a visit to the house of Dr. Stuart! I determined to call upon the doctor. As it chanced I was delayed and did not actually arrive until so late an hour that I had almost decided not to present myself ... when a big yellow car flashed past the taxicab in which I was driving! _Nom d'un nom!_ I could not mistake it! This was within a few hundred yards of the house of Dr. Stuart, you understand, and I instantly dismissed my cabman and proceeded to advance cautiously on foot. I could no longer hear the engine of the car which had passed ahead of me, but then I knew that it could run almost noiselessly. As I crept along in that friendly shadow cast by a high hedge which had served me so well before, I saw the yellow car. It was standing on the opposite side of the road. I reached the tradesman's entrance. From my left, in the direction of the back lawn of the house, came a sudden singular crackling noise and I discerned a flash of blue flame resembling faint "summer lightning." A series of muffled explosions followed ... and in the darkness I tripped over something which lay along the ground at my feet--a length of cable it seemed to be. Stumbling, I uttered a slight exclamation ... and instantly received a blow on the head that knocked me flat upon the ground! Everything was swimming around me, but I realized that someone--Chunda Lal probably--had been hiding in the very passage which I had entered! I heard again that uncanny wailing, close beside me.