"You're a case for an ordinary human physician now, Costigan," he said. "Even a layman like myself can tell that. For the first time since I've known you, the look in your eyes is entirely sane. You look like a man who has had a complete nervous breakdown, and needs about a year of rest and quiet. Great heavens, man, you've been through enough, outside your dope experience, to last you a lifetime." "Tell me first," said I: "Was Kathulos killed in the explosion?" "I don't know," answered Gordon somberly. "Apparently the entire system of subterranean passages was destroyed. I know my last bullet--the last bullet that was in the revolver which I wrested from one of my attackers--found its mark in the Master's body, but whether he died from the wound, or whether a bullet can hurt him, I do not know. And whether in his death agonies he ignited the tons and tons of high explosives which were stored in the corridors, or whether the negroes did it unintentionally, we shall never know. "My God, Costigan, did you ever see such a honeycomb? And we know not how many miles in either direction the passages reached. Even now Scotland Yard men are combing the subways and basements of the town for secret openings. All known openings, such as the one through which we came and the one in Soho 48, were blocked by falling walls. The office building was simply blown to atoms." "What about the men who raided Soho 48?" "The door in the library wall had been closed. They found the Chinaman you killed, but searched the house without avail. Lucky for them, too, else they had doubtless been in the tunnels when the explosion came, and perished with the hundreds of negroes who must have died then." "Every negro in London must have been there." "I dare say. Most of them are voodoo worshipers at heart and the power the Master wielded was incredible. They died, but what of him? Was he blown to atoms by the stuff which he had secretly stored, or crushed when the stone walls crumbled and the ceilings came thundering down?" "There is no way to search among those subterranean ruins, I suppose?" "None whatever. When the walls caved in, the tons of earth upheld by the ceilings also came crashing down, filling the corridors with dirt and broken stone, blocking them forever. And on the surface of the earth, the houses which the vibration shook down were heaped high in utter ruins. What happened in those terrible corridors must remain forever a mystery." * * * * * My tale draws to a close. The months that followed passed uneventfully, except for the growing happiness which to me was paradise, but which would bore you were I to relate it. But one day Gordon and I again discussed the mysterious happenings that had had their being under the grim hand of the Master.