For a few moments I held her in my arms tenderly, then releasing her, she bade me _au revoir_ merrily, and we descended into the hall together. A taxi was called, and I heard her direct the driver to go to the Boulevard Pereire. Then, waving her hand from the cab window, she drove away. Should I follow? To spy upon her would be a mean action. It would show a lack of confidence, and would certainly irritate and annoy her. Yet was she not in peril? Had she not long ago admitted herself to be in some grave and mysterious danger? I had only a single moment in which to decide. Somehow I felt impelled to follow and watch that she came to no harm; yet, at the same time, I knew that it was not right. She was my wife, and I dearly loved her and trusted her. If discovered, my action would show her that I was suspicious. Still I felt distinctly apprehensive, and it was that apprehension which caused me, a second later, to seize my hat, and, walking out of the hotel, hail a passing taxi, and drive quickly to the quiet, highly respectable boulevard to which she had directed her driver. I suppose it was, perhaps, a quarter of an hour later when we turned into the thoroughfare down the centre of which runs the railway in a deep cutting. The houses were large ones, let out in fine flats, the residences mostly of the professional and wealthier tradesman classes. We went along, until presently I caught sight of another taxi standing at the kerb. Therefore I dismissed mine, and, keeping well in the shadow, sauntered along the boulevard, now quiet and deserted. With great precaution I approached the standing taxi on the opposite side of the way. There was nobody within. It was evidently awaiting some one, and as it was the only one in sight I concluded that it must be the same which Sylvia had taken from the hotel. Some distance further on I walked, when, before me, I recognized her neat figure, and almost a moment afterwards saw her disappear into a large doorway which was in complete darkness--the doorway of what seemed to be an untenanted house. I halted quickly and waited--yet almost ashamed of myself for spying thus. A moment later I saw that, having believed herself unobserved, she struck a match, but for what reason did not seem apparent. She appeared to be examining the wall. She certainly was not endeavouring to open the door. From the distance, however, I was unable to distinguish very plainly. The vesta burned out, and she threw it upon the ground. Then she hurriedly retraced her steps to where she had left her cab, and I was compelled to bolt into a doorway in order to evade her. She passed quite close to me, and when she had driven away I emerged, and, walking to the doorway, also struck a light and examined the same stone wall. At first I could discover nothing, but after considerable searching my eyes at last detected a dark smudge, as though something had been obliterated.