The distant sound died away entirely. A clock began to strike; it struck the half-hour. In an instant my handkerchief was off, and so was Smith's. We stood upon a towing-path. Away to the left the moon shone upon the towers and battlements of an ancient fortress. It was Windsor Castle. "Half-past ten," cried Smith. "Two hours to save Graham Guthrie!" We had exactly fourteen minutes in which to catch the last train to Waterloo; and we caught it. But I sank into a corner of the compartment in a state bordering upon collapse. Neither of us, I think, could have managed another twenty yards. With a lesser stake than a human life at issue, I doubt if we should have attempted that dash to Windsor station. "Due at Waterloo at eleven-fifty-one," panted Smith. "That gives us thirty-nine minutes to get to the other side of the river and reach his hotel." "Where in Heaven's name is that house situated? Did we come up or down stream?" "I couldn't determine. But at any rate, it stands close to the riverside. It should be merely a question of time to identify it. I shall set Scotland Yard to work immediately; but I am hoping for nothing. Our escape will warn him." I said no more for a time, sitting wiping the perspiration from my forehead and watching my friend load his cracked briar with the broadcut Latakia mixture. "Smith," I said at last, "what was that horrible wailing we heard, and what did Fu-Manchu mean when he referred to Rangoon? I noticed how it affected you." My friend nodded and lighted his pipe. "There was a ghastly business there in 1908 or early in 1909," he replied: "an utterly mysterious epidemic. And this beastly wailing was associated with it." "In what way? And what do you mean by an epidemic?" "It began, I believe, at the Palace Mansions Hotel, in the cantonments. A young American, whose name I cannot recall, was staying there on business connected with some new iron buildings. One night he went to his room, locked the door, and jumped out of the window into the courtyard. Broke his neck, of course." "Suicide?" "Apparently. But there were singular features in the case. For instance, his revolver lay beside him, fully loaded!" "In the courtyard?" "In the courtyard!" "Was it murder by any chance?" Smith shrugged his shoulders. "His door was found locked from the inside; had to be broken in." "But the wailing business?" "That began later, or was only noticed later. A French doctor, named Lafitte, died in exactly the same way." "At the same place?" "At the same hotel; but he occupied a different room. Here is the extraordinary part of the affair: a friend shared the room with him, and actually saw him go!" "Saw him leap from the window?"