At the very moment that this thought came, I saw from my position under the shadow of a spreading oak, which has not yet dropped its leaves, that I was not the only person who was observing the light behind the blinds. A figure was standing not more than a hundred feet away from me, peering out from beyond one of the light poles. It wore a vizored cap, I thought, and its head rolled this way and that on top of its spare, bent, and agile body. Now and then, however, it ceased this grotesque movement to gaze up at the window. One would have said that this creature was less a man than an ape. I am not a coward. "Here," thought I, "is a tangible factor. My word of honor to Julianna is not broken if I seize this customer, whatever he may be, and make him explain the part he is acting." I stepped forward immediately, but he saw me before I had made two steps. From my bearing and the place where I had concealed myself, he knew at once, I suppose, that I had been watching him, for, turning with a swift motion, he plunged into the shrubs and evergreens behind him. That the thing was as frightened as a rabbit, there can be no doubt; the single little cry it gave forth was not a scream. You would have called it a squeal! In a jiffy I was after him, tearing through the branches among which, with a sinuous twisting of his body, he had just slid; a moment later I reached the open lawn again. The man had vanished. I knew well enough that he was hiding, probably flattened on the ground, among the evergreens. At another time, on a quiet evening, listening for his movements or even his breathing, might have told me where he lay, but now the wind and the rattle of dead leaves made it necessary for me to use my eyes in my search. Therefore I went back through the bushes, kicking at dark shadows with my foot, my heart thumping with the excitement of the hunt. As I reached the street again, I looked up toward my house, and there, at the front door, I saw a crack widen and a black figure of a man come out and down the steps. It crossed the street, and when it had gone into the park, I followed it. You know what happened; this second man was you. And now I ask you, Doctor, man to man--For God's sake, tell me what you know! BOOK III THE DOCTOR'S LIMOUSINE CHAPTER I A SHADOW ON THE CURTAIN