For a moment, I admit, I paused, paralysed by a nameless horror. Immediately afterwards the utter absurdity of any serious cause for fright on a ground floor in a thoroughfare not a dozen yards from the never-dying turmoil of the Strand broke upon me. With one bound I sprang to my office door, which I instantly flung far open, and there immediately entered to me, without a word being uttered on either side, a tall, thin, foreign-looking man of about twenty-five. His was the face which I had seen staring at me so eagerly through the window-pane! "Pardon me coming at this unseasonable hour," he said, with a profound gesture of humility, yet in a gentle, refined accent that suggested the student and the scholar. "Permit me to introduce myself," and, with a flourish, he handed me a large-sized card, on which was engraved the name, in a distinctly foreign hand, "Don Jose Casteno," but the address was scratched out. For an instant his eyes met mine in one long, keen, lingering gaze of scrutiny--in that fatal instant, indeed, which follows the coming together of all men destined to do much in common, and which I have always found, in my experience, invariably decides whether we trust or we hate. Strange as his arrival had been, I will say, frankly, I took a liking to him even in that ghostly glare of the firelight; and, motioning him to a chair opposite to my desk, I turned up the gas. Then as he removed a wide-brimmed felt hat and unfastened a shabby black coat with a kind of Inverness cape, most often seen in use by foreign priests, I noticed his pale, intellectual-looking, clean-shaven face, with a mouth as tender and expressive as a girl's. "My business," he began in a low voice of explanation as soon as he saw me seat myself and take up a pen to follow him, "is by no means a piece of common detective work which I am anxious that you should undertake in my behalf. On the contrary, it deals, Mr Glynn," and now his voice became very grave, "with much that is startling and mysterious--much that spells ugly words like `treachery' even in London--striking, as it does, at the root of at least one far-reaching unprincipled, foreign intrigue. First of all, then, I must ask you to tell me quite openly and frankly, are you free and prepared to undertake a series of difficult and dangerous missions?" "I am," I replied after a moment's pause; "but it must be on terms." "And what are those terms?" "First, that I am well and punctually paid," and, in spite of myself, I smiled, for I found quite suddenly I had grown quite mercenary after my bitter reflections about Doris.