In hesitancy I remained some little time, then a sudden thought occurred to me. I addressed an envelope to the hall-porter of my club, enclosing a blank sheet of paper, and then descending, posted it. The box was placed outside the bureau, and the instant I had dropped the letter in I turned, as though in anger with myself, and, entering the bureau, said to the clerk-- "I've unfortunately posted a letter without a stamp. Have you the key of the box?" "The box belongs to the Post Office, sir," he answered. "But we have a key to it." "Then I should esteem it a favour if you would recover my letter for me. It is most important that the addressee should not be charged for its postage. I regret that my absent-mindedness should give you this trouble." The clerk took the key from a drawer at the end of the bureau, and opening the box, took out the half-dozen or so letters which it contained, and spread them upon the desk. Among them were two square, pale-faced envelopes. As I took my own letter and affixed a stamp I glanced eagerly at the address of both. One bore the superscription: "Mr P. Gechkuloff, 98, King Henry's Road, Hampstead, N.W." Upon the other were words which caused my heart to leap joyfully within me. They were-- "Miss Mabel Anson, _Langham Hotel_, London." I posted my letter, hurried upstairs and paid my bill. Edna had already packed her trunk, but had changed her mind, and did not intend leaving Hull that day. I heard her inform the chambermaid of her intention of remaining, then I left the hotel, and caught the ten-forty-five express for London. CHAPTER TWENTY NINE. THE ENIGMA. At five o'clock that same afternoon I alighted from a taxi before the _Langham Hotel_, and presenting my card at the bureau, inquired for Miss Anson. The clerk looked at me rather curiously, I thought, glanced at the card, and entering the telephone-box, spoke some words into the instrument. I was shown into a small room on the first floor, where I waited until a gentlemanly, middle-aged, fair-headed man entered, with my card in his hand. "Good afternoon," he said, greeting me rather stiffly. "Her Highness is at present out driving. Is there anything I can do? I am her secretary." "Her Highness?" I echoed, with a smile. "There must be some mistake. I have called to see Miss Mabel Anson." He regarded me with some surprise. "Are you, then, unaware that Anson is the name adopted by Her Highness to preserve her _incognita_?" he asked, glancing at me in quick suspicion. "Are you not aware of her real rank and station?" "No!" I cried, in blank amazement. "This is indeed a revelation to me! I have known Miss Anson intimately during the past six years. What is her true rank?" "The lady whom you know as Miss Anson is Her Imperial Highness the Archduchess Marie Elizabeth Mabel, third daughter of His Majesty the Emperor Francis Joseph of Austria." "Mabel! The daughter of an Emperor?" I gasped involuntarily. "Impossible!"