"She is ignorant of the truth," he said, with a grim smile. "Well, this evening, it appears, the dead man's daughter returns in secret, enters with her latch-key the house where her father is lying, removes her hat carefully, and then--" "Yes," I said. "And then? What do you believe occurred?" He was silent, his deep-set eyes downcast in thought. "Well, I--I hardly know what to think," he declared. "It almost seems as though she shared the same fate as her father. That horrible disfiguration is most remarkable." "Her entry here in secret and the strange fate that has overtaken her increases the mystery tenfold!" I declared. "Why didn't she call Antonio?" "Perhaps that was her intention, but she was prevented," suggested my friend. And I saw that his glance was fixed upon me curiously, as though he were deliberately gauging my character and intelligence. "But to me it appears as though her intention might have been to reach the laboratory unobserved," I said. "She may, indeed, have been up here for aught we know to the contrary." "I hardly think so. She was far too horrified at sight of the body of her father, to whom she was so devoted. The scene when she saw him dead was very painful." "But might she not have been induced to return by morbid curiosity?" I suggested. "You've already told me that she was beside herself with grief." "Well," he replied, with a sigh and a final glance across to where the dark object was huddled in the opposite corner, "no purpose, I think, can be served by remaining here longer to-night. We must return in the morning. I only brought you here in order that you might fully understand the exact problem now before us. Come along." "But I don't see, Mr. Kirk, how it is possible for me to help you. I'm quite a novice in this kind of thing," I said. "You are not a detective. If you were, I should not seek your aid," he snapped, as he led the way to the door and switched off the lights. "I know you think it rather strange that I have not called a doctor and the police, and had a post-mortem, and allowed the newspaper reporters to `work up' a big sensation; but, as I've already told you, our success depends upon absolute secrecy. The affair is a startling one to you, no doubt; but if you were aware of what the tragedy really means you would be dumbfounded. Why, the newspapers could make a world-wide sensation of it if only they got at the true facts; but they never will, I assure you--never." "Then even I may not know the true facts?" I asked, as I stood with him again in the boudoir. "As far as the tragedy is concerned, you already know them. They are just as I have told you. But there are other facts--facts concerning myself and also the Professor--which I am not permitted to divulge. They must," he added, "remain a secret."