It must have been the clock striking, I concluded, presently; and was commencing to doze off, when a sudden noise brought me back, once more, to life. It was the sound of a step, as of a person moving cautiously down the corridor, toward my study. In an instant, I was on my feet, and grasping my rifle. Noiselessly, I waited. Had the creatures broken in, whilst I slept? Even as I questioned, the steps reached my door, halted momentarily, and then continued down the passage. Silently, I tiptoed to the doorway, and peeped out. Then, I experienced such a feeling of relief, as must a reprieved criminal--it was my sister. She was going toward the stairs. I stepped into the hall, and was about to call to her, when it occurred to me, that it was very queer she should have crept past my door, in that stealthy manner. I was puzzled, and, for one brief moment, the thought occupied my mind, that it was not she, but some fresh mystery of the house. Then, as I caught a glimpse of her old petticoat, the thought passed as quickly as it had come, and I half laughed. There could be no mistaking that ancient garment. Yet, I wondered what she was doing; and, remembering her condition of mind, on the previous day, I felt that it might be best to follow, quietly--taking care not to alarm her--and see what she was going to do. If she behaved rationally, well and good; if not, I should have to take steps to restrain her. I could run no unnecessary risks, under the danger that threatened us. Quickly, I reached the head of the stairs, and paused a moment. Then, I heard a sound that sent me leaping down, at a mad rate--it was the rattle of bolts being unshot. That foolish sister of mine was actually unbarring the back door. Just as her hand was on the last bolt, I reached her. She had not seen me, and, the first thing she knew, I had hold of her arm. She glanced up quickly, like a frightened animal, and screamed aloud. 'Come, Mary!' I said, sternly, 'what's the meaning of this nonsense? Do you mean to tell me you don't understand the danger, that you try to throw our two lives away in this fashion!' To this, she replied nothing; only trembled, violently, gasping and sobbing, as though in the last extremity of fear. Through some minutes, I reasoned with her; pointing out the need for caution, and asking her to be brave. There was little to be afraid of now, I explained--and, I tried to believe that I spoke the truth--but she must be sensible, and not attempt to leave the house for a few days. At last, I ceased, in despair. It was no use talking to her; she was, obviously, not quite herself for the time being. Finally, I told her she had better go to her room, if she could not behave rationally. Still, she took not any notice. So, without more ado, I picked her up in my arms, and carried her there. At first, she screamed, wildly; but had relapsed into silent trembling, by the time I reached the stairs.