He stopped for an instant, not in indecision this time, but in a grim resolution to let no chance escape him now. The car was going slowly; it was easy to board it now, but again the tinkle of the bell indicated that it was stopping at the corner of a road beyond. He checked his pace,--a lady alighted,--it was she! She turned into the cross-street, darkened with the shadows of some low suburban tenement houses, and he boldly followed. He was fully determined to find out her secret, and even, if necessary, to accost her for that purpose. He was perfectly aware what he was doing, and all its risks and penalties; he knew the audacity of such an introduction, but he felt in his left-hand pocket for the sprig of fern which was an excuse for it; he knew the danger of following a possible confidante of desperadoes, but he felt in his right-hand pocket for the derringer that was equal to it. They were both there; he was ready. He was nearing the convent and the oldest and most ruinous part of the town. He did not disguise from himself the gloomy significance of this; even in the old days the crumbling adobe buildings that abutted on the old garden wall of the convent were the haunts of lawless Mexicans and vagabond peons. As the roadway began to be rough and uneven, and the gaunt outlines of the sagging roofs of tiles stood out against the sky above the lurking shadows of ruined doorways, he was prepared for the worst. As the crumbling but still massive walls of the convent garden loomed ahead, the tall, graceful, black-gowned figure he was following presently turned into the shadow of the wall itself. He quickened his pace, lest it should again escape him. Suddenly it stopped, and remained motionless. He stopped, too. At the same moment it vanished! He ran quickly forward to where it had stood, and found himself before a large iron gate, with a smaller one in the centre, that had just clanged to on its rusty hinges. He rubbed his eyes!--the place, the gate, the wall, were all strangely familiar! Then he stepped back into the roadway, and looked at it again. He was not mistaken. He was standing before the porter's lodge of the Convent of the Sacred Heart. CHAPTER V.