And still I failed to grasp the mysterious connection between the vast unknown island lying on the Equator and the tragedy I had all but witnessed in a night club of London. “You can take my card,” the specialist added. “You will find the people at the Museum most obliging. If they have the information they will give it to you willingly.” I took the card, and the Piccadilly Tube from Russell Square soon landed me at South Kensington. As Sir Frank Tarleton had foretold, the staff of the Natural History Museum received it with all respect, and showed themselves ready to give all the information they possessed. The gentleman who took me in hand was confident that there were leopards in Sumatra; nevertheless, when it came to the question of positive evidence he found some difficulty in putting his hand on any. “You have struck the least-known area in the world, you see,” he pointed out. “We know the fauna of the Malay Peninsula, and of Java and all the other East Indian islands as far as the Philippines, and one has always taken it for granted that the fauna of Sumatra corresponded with that of the neighbouring area north of the Wallace line. But if you ask me for an official declaration that leopards are to be found in the island I don’t think I can give it off-hand. We might be able to get the information by writing to The Hague. Or you might find it in some book of travels in the British Museum Library.” “Sir Frank Tarleton is searching in the Library at this moment, I believe,” I said incautiously. My guide opened his eyes. “You surprise me. I had no idea that Sir Frank was so much interested in natural history. I have always associated his name with toxicology.” The light burst on me at last. I understood the true reason for my chief’s extreme interest in following up the clue of the leopard’s claws, and for his turning his special attention to the region of the earth least known to science. He had perceived a connection overlooked by me between the rare necklace worn by the unknown woman in the Domino Club and the gray powder contained in the small glass bottle in his private safe. He was on the search for some other product of Sumatra besides its leopards. He expected to trace the secret drug whose presence the effects of the opium had concealed. CHAPTER IX SARAH NEOBARD SPEAKS OUT When I returned to Montague Street to lunch, my host was still out, and I had to sit down to the meal without him. No uncommon incident this, in the case of any member of the medical profession, and especially one liable to be summoned at any moment to cases of the most desperate nature. Yet I was uneasy at losing sight of the great man for so long just then. The investigation had reached a point at which I was desperately anxious to follow his every move, in order that I might guard the threatened girl towards whom so many signs already seemed to point.