"Father received a letter. It came one afternoon when I had returned from the club earlier than usual. I took it from the postman myself, and as father had not come home yet from the shop, I placed it beside his plate at the supper table. I noticed the postmark--'Brooklyn'--but it didn't make any particular impression upon me; it was only later, when I saw how it affected my father, that I remembered, and wondered. He had scarcely opened the envelope, when he rose, trembling so that he could hardly stand, and coming into this room, he shut the door after him. I waited as long as I could, but he did not return, and the supper was getting cold, so I came to the door here. It was locked! For the first time in his life, my father had locked himself in, from me! He would not answer me at first, as I called to him, and I was nearly frightened to death before he spoke. When he did, his voice sounded so harsh and strained that I scarcely recognized it. He told me that he didn't want anything to eat; he had some private business to attend to, and I was not to wait up for him, but to go to bed when I wished. "I crept away, and went to my room at last, but I could not sleep. It was nearly morning when Father went to bed, and his step was heavy and dragging as he passed my door. His room is next to mine, and I heard him tossing restlessly about--and once or twice I fancied that he groaned as if in pain. He was up in the morning at his usual time, but he looked ill and worn, as if he had aged years in that one night. Neither of us mentioned the letter, then or at any subsequent time, but he has never been the same man since." "And the letter--you never saw it?" Morrow asked eagerly, his detective instinct now thoroughly aroused. "You don't know what that envelope postmarked 'Brooklyn' contained?" "Oh, but I do!" Emily exclaimed. "Father had thrust it in the stove, but the fire had gone out, without his noticing it. I found it the next morning, when I raked down the ashes." "You--read it?" Morrow carefully steadied his voice. "No," she shook her head, with a faint smile. "That's the queer part of it all. No one could have read it--no one who did not hold the key to it, I mean. It was written in some secret code or cipher, with oddly shaped figures instead of letters; dots and cubes and triangles. I never saw anything like it before. I couldn't understand why anyone should send such a funny message to my father, instead of writing it out properly." "What did you do with the letter--did you destroy it?" This time the detective made no effort to control the eagerness in his tones, but the girl was so absorbed in her problem that she was oblivious to all else.