To me, I confess, the solution of the mystery seemed now to be well in sight. On our return to town I expected to find that Inspector Charles had ascertained the present whereabouts of the explorer of Sumatra. From him it should not be difficult to learn the identity of the Leopardess, as I called her in my own mind; and I took it for granted that she was a victim of Weathered’s who had delivered herself out of his power by the use of the deadly fungus of the upas. My one anxiety at present was the thought of the missing letters. I wearied myself with speculating as to whose hands they had passed into since the murder, and by what means they could be recovered and destroyed without their contents becoming known. I was as far as ever from seeing my way clearly when we arrived in Montague Street that evening. A serious disappointment waited for us there. An official envelope stamped with the seal of New Scotland Yard lay on the table in the hall. Before I had closed the front door Tarleton had pounced upon it, torn it open, and scanned the note inside with an impatient scowl. “Fool!” He almost flung the Inspector’s communication in my face. It stated briefly that Captain Armstrong had met his death by malarial fever in Yucatan six months ago; and that was all. I hardly know what more Charles could have said, since he was quite ignorant why the explorer’s address was wanted. Tarleton sometimes failed to allow for the fact that his assistants were not all gifted with his own quickness of apprehension. However, I didn’t venture to defend the delinquent. My chief’s irritation soon subsided, and as soon as we were seated at a well-spread table he acquitted the Inspector handsomely. “After all, I didn’t take Charles into my confidence, as I have taken you, Cassilis. But now we must set to work in earnest. What do you suggest as the next step?” The question was too much for me, as I had to confess. Perhaps I was too much worried about the letters to be able to give my mind to anything else. The consultant smiled good-naturedly. “Our only clue to Captain Armstrong’s friend is his book. Books are produced by publishers, and publishers pay royalties. By this time the publisher of _Across Sumatra_ ought to have heard from Armstrong’s executor. And the executor should be able to put us on the track of the person who has come into possession of his effects.” He paused to let this reasoning sink into my mind before he added, “I think this greatly simplifies matters. It is much more likely that Armstrong kept some of the upasine himself among his trophies than that he gave it away, to a woman, above all. Depend upon it, we shall find that it passed on his death to the lady of the leopard’s claws.” He seemed about to say more but broke off abruptly, as though a new thought had struck him. “She will have to be handled carefully,” was all he said after a short silence.