"Very well, then," I said, "let us turn our attention to the other possibility. Assuming that he has got away, I think we may safely say that the danger is very much lessened." "While we remain here in the City--yes," Morse agreed. "And you are determined to do that?" He took the cigar he had been smoking from his lips, and his hand shook a little. "Think what you like of me," he said, "but remember that there is Juanita. I say to you, Kirby, that if I never descend to the world again alive, I must stay here until Mark Antony Midwinter is dead." Well, I had already made up my mind on this point. "I think you are quite right," I told him. "Still, he will not make a second appearance in the City. You can treble your precautions. He must be attacked down in the world." Then a thought struck me for the first time. "But how," I said, "did he and Zorilla ever come here in the first instance? Treachery among the staff? It is the only explanation." Pu-Yi shook his head. "You may put that out of your mind, Sir Thomas," he said. "That is my department. I know what you cannot know about my chosen compatriots." "But the man isn't a specter! He's a devil incarnate, but there's nothing supernatural about him." Then little Rolston spoke. "I've been down below all day," he said, "and though I haven't discovered anything of Midwinter, I am certain of how he and Zorilla got here." We all turned to him with startled faces. "Do you remember, Sir Thomas," he said, "that, shortly after your arrival, when you were looking down upon London from one of the galleries, there was a big fair in Richmond Park?" I remembered, and said so. "Among the other attractions, there was a captive balloon--" Morse brought his hand heavily down upon the table with a loud exclamation in Spanish. "Yes, there was, but--but it was quite half a mile away and never came up anything like our height here." "No," the boy answered, "not at that time. But do you remember how during the fog last night I told you I had seen something, or thought I had seen something, like a group of statuary falling before my bedroom window?" Something seemed to snap in my mind. "Good heavens! And I thought it was merely a trick of the mist! Nothing was discovered?"