Before my marriage my father, as fathers will, had looked upon her with considerable misgiving. She was a little too flighty, too fond of dress, of dinners, and dances, he had said. But after our wedding and our honeymoon spent in a car touring up in Scotland, she had settled down, and never for a single instant had I regretted my choice. Few men could say that. Indeed, up to that day when Kershaw Kirk called to inspect the Eckhardt tyre, I was one of the happiest men in all London; prosperous in my business, and contented in my love. Now, alas! all had changed. I was obsessed by the knowledge of a great and startling secret, and at the same time I had lost all that to me was most dear and cherished. Next morning Gwen, fresh in her clean cotton blouse, and the big black bow in her hair, sat in her accustomed place at the breakfast table, but after greeting me lapsed into a thoughtful silence. At last she asked: "Have you packed your things, Harry?" "Oh, I forgot to tell you!" I exclaimed. "I'm not going to-day. I've changed my mind." "Not going? Why, I thought you intended to see the Professor in Strassburg?" she cried. "He has left," I sighed; "I learned last night that he is on his way to Hungary." "And will you not follow?" asked the girl in reproach. "Will you not try to discover where Mabel is?" "I've tried, Gwen--and failed," I answered despairingly. "You have not told me all, Harry," she said, looking across at me. At the head of the table was Mabel's empty place. "You have concealed something from me," she declared. "It is nothing that you should know," was my quick reply. "My own private business does not concern you, Gwen--or Mabel either." "But surely I ought to know the truth? Mabel has been decoyed away abroad, and there must be some motive for it," she replied in bitter complaint. "Of course, my dear girl, but even I, in the knowledge of what has passed, cannot discern what the motive can be. If I could, all would be plain sailing, and we would soon recover her," I said. "Who is this Professor of whom you have spoken?" she asked, leaning her elbows upon the table, and gazing straight into my eyes. "Professor Greer, the well-known chemist." "Greer?" echoed the girl, staring at me strangely. "Yes, why?" But she hesitated, as though disinclined to tell me something which was upon her mind. "You know the Professor, eh, Harry?" "I've met him once," I replied, which was perfectly true. "And only once?" she asked. "Only once," was my quick response. "That's curious." "Why?" "Well--well, I suppose I ought not to tell you, for, of course, Harry-- it's no business of mine," remarked the girl, "but as Mabel is now missing, no fact should be concealed, and I think you really ought to know that--" "That what?" I cried. "Tell me quickly, Gwen! Conceal nothing from me!"