"The condition I impose upon you in return for my assistance," she said, in deepest earnestness, "is that you shall promise to render assistance to a person who will ever remain unknown to you. Any requests made to you will be by letter bearing the signature A-V-E-L, and these instructions you must promise to obey without seeking to discover either motive or reason. The latter can never be made plain to you, therefore do not puzzle yourself unnecessarily over them, for it will be all to no purpose. The secret--for secret there is, of course--will be so well guarded that it can never be exposed, therefore if you consent to thus rendering me a personal assistance in return for your life, it will be necessary to act blindly and carry out to the letter whatever instructions you receive, no matter how remarkable or how illogical they may seem. Do you agree?" "Well," I said hesitatingly, "your request is indeed a most extraordinary one. If I promise, what safeguard have I for my own interests?" "Sometimes you may, of course, be compelled to act against your own inclinations," she admitted. "I, however, can only assure you that if you make this promise I will constitute myself your protectress, and at the same time give you solemn assurance that no request contained in the letters of which I have spoken will be of such a character as to cause you to commit any offence against the law." "Then it is you yourself who will be my anonymous correspondent?" I observed quickly. "Ah, no!" she answered. "That is, of course, the natural conclusion; but I may as well at once assure you that such will not be the case." Then she added, "I merely ask you to accept or decline. If the former, I will ever be at your service, although we must never meet again after to-day; if the latter, then I will wish you adieu, and the terrible fate your unknown enemies have prepared for you must be allowed to take effect." "But I should be drowned!" I exclaimed in alarm. "Surely you will not abandon me!" "Not if you will consent to ally yourself with me." "For evil?" I suggested very dubiously. "No, for good," she answered. "I require your silence, and I desire that you should render assistance to one who is sorely in need of a friend." "Financial aid?" "No, finance has nothing to do with it. The unknown person has money and to spare. It is a devoted personal assistance and obedience that is required." "But how can one be devoted to a person one has neither seen nor known?" I queried, for her words had increased the mystery. The shrewd suspicion grew upon me that this curious effort to secure my silence was because of her own guilt; that she intended to bind me to a compact in her own nefarious interests. "I am quite well aware of the strangeness of the conditions I am imposing upon you, but they are necessary." "And if I accept them will the mystery of to-night ever be explained?" I inquired, eager to learn the truth.