"Is that any of your business?" she asked, her eyes beginning to gleam. "Perhaps not," I admitted. "And yet you're capable of making a mystery out of it!" she sneered. "Let me relieve your mind--I'm staying with Mrs. Lawrence. She sleeps badly, and wishes me near her." "And your exits and entrances are, I suppose, usually by the window?" "It's the most convenient way." "Mrs. Lawrence doesn't object, then, to your leaving it open?" "I don't leave it open." "You did just now." She looked at me a moment without replying, then laughed a short, little laugh of mingled amusement and vexation. "I'll leave you to puzzle that out, I think," she said. "You're so ingenious, you'll surely hit upon the explanation. I scarcely expected to see you here again," she added. "You thought it worth while to return?" "Yes; there are one or two points which are not quite clear." "And you expect to make them so?" she asked, with a mocking smile. "How? By lurking around the house like a thief, and following women?" There was something in her tone, her look, her attitude, which caught my attention--a sort of confident triumph, as of one who plays for a high stake and wins. She was no longer anxious and perturbed, as she had been the day before--nay, that very morning. She thought it safe to flout me openly. "So you convinced Mrs. Lawrence that you and your sister were not guilty?" I asked. "But of course you'd do that!" "Guilty of what?" she demanded, flushing darkly. "Guilty of causing Miss Lawrence's flight," I answered bluntly. "Of wrecking her life." "Do you believe that?" "I know it!" She laughed scornfully. "You know a great deal, it seems." "More than you think," I retorted. She flushed again, and bit her lips to restrain their trembling. "Though there's one thing I don't know," I went on, determined to strike home, if I could. "I can't imagine why Miss Lawrence should have chosen your house as a place of refuge. She must know that you hate her--that you waited, like a snake in ambush, for the moment when the blow would pierce most deeply; she must see that you are using her to avenge yourself----" A sharp click interrupted me, and I found myself in darkness. I heard the closing of a door, the turning of a lock. When, after a moment's groping along the wall, I found the electric button and switched on the light again, I saw that the door leading from the library to the hall was closed. I tried it--it was locked. "Good-night, Mr. Lester," called a low mocking voice from the other side. "Please turn off the light before you go, and close the window after you. Another thing--I'd advise you not to disturb my sister again to-night; it would really not be safe. And I hope you'll let me know when you succeed in clearing up those little points you were speaking of--I'm immensely interested in them." She laughed again, and I heard her footsteps die away down the hall.