Not one single instant did I doubt Mabel's truth and love. If she had met this impostor, then she had been the victim of some cleverly-planned plot. I was incensed only against the perpetrators of that foul crime in Sussex Place, not against the sweet, soft-spoken woman who was so near my heart. Mabel was my wife, my love, my all-in-all. Poor Gwen, watching my face intently, believed that she had acted as a sneak towards her sister, but I quickly reassured her that it was not so. Her revelations had sent my thoughts into a different channel. "The telegram summoning her to Italy came after her return?" I asked. "Yes, she was upset, and would eat no tea," the girl answered. "Her conversation was all the time of you. `Harry is in danger,' she said several times. `Something tells me that he is in the greatest danger.' Then, when the message came, she became almost frantic in her anxiety for your welfare, saying, `Did I not tell you so? My husband is in peril. He is the victim of a plot!'" "You never heard her speak of the Professor before?" I inquired. "Never, Harry; and, truth to tell, I was surprised that she should receive a letter from a man who she admitted to me was unknown to you." "She told you that?" I cried. "She said that you were not acquainted with the Professor, and that you might object to him writing to her, if you knew." "Then she was in fear of discovery, eh?" I asked in a husky voice. "Yes," faltered the girl. "It--it almost seemed as though she was. But really, Harry, I--I know I've done wrong to tell you all this. I--I'm quite ashamed of myself. But it is because I am in such great fear that something has happened to my sister." "You have done quite right, Gwen," I assured her. "The circumstances have warranted your outspokenness. Some men might perhaps misjudge their wives in such a case, but I love Mabel, and she loves me. Therefore I will believe no ill of her. She is the innocent victim of a plot, and by Heaven!" I cried fiercely, "while I live I'll devote my whole life to its exposure, and to the just punishment of any who have dared to harm her!" CHAPTER TWENTY. ONE TRAVELLER RETURNS. One fact was quite plain. It was the false Professor who had written to my wife. For aught I knew, the man whom I had followed from Edinburgh to Glasgow might have already been in London, and she might have met him by appointment. During the morning I took the "forty-eight," and ran over to Regent's Park, passing slowly before both front and back of the house in Sussex Place. The blinds were up, but from the condition of the doorsteps it was plain that the place was tenantless. From the "London Directory" I obtained the number of Lady Mellor's, in Upper Brook Street, and called. The fat butler told me that Morgan, Miss Greer's maid, had left with her mistress, and as far as he knew was down at Broadstairs with her. Her ladyship was at Bordighera.