“We’ve gone over the whole room again, sir; and also the rooms adjoining. Everything is in order,” he reported. “Particularly the pipes?” Sencort asked. “There’s nothing wrong with the pipes, sir.” “Very well,” Sencort dismissed him; and then he looked at me. “Much obliged, Fanneal,” he thanked me again. Of course, he was dismissing me, but I held my ground. “The warning which reached me, Mr. Sencort, did not advise mere examination of the room,” I insisted. “It said to prevent its use. I must urge you, whatever you think, not to meet in that room.” “Fanneal, if I governed my movements according to cautions of well-meaning friends, I’d have put myself and family and friends in a steel safe thirty years ago. Reed says that room is clear; it is on the fifth floor, so attack from the street is impossible. Here’s Teverson now.” Another hint for me, but I stuck, and just then Teverson came in to see what was so absorbing in here, and old Sencort, in explaining why he was preferring a chat with me to a conference with M. Géroud and Lord Strathon at that hour, of course dragged in the mad idea I’d brought along. But Teverson wasn’t amused by it at all. “Reed and Weston have both examined the room,” Sencort repeated, “and found all in order.” “All was in order over at Ed Costrelman’s the other night, not only before but after the--the occurrence,” Teverson mentioned in a thoughtful sort of brooding manner which sparked up old Sencort. “What occurrence?” he came back loudly; of course Teverson had the door shut after him. “Good Lord,” said Teverson, “didn’t you know that Ed Costrelman’s dead?” “Certainly,” said Sencort. “I also know that his butler is dead and most of his party was sick but have recovered; from something wrong in the wine or vermuth. What has that to do with us? We’re not serving liqueur at directors’ meeting.” “It wasn’t in the wine or vermuth,” Teverson came back calmly. “It wasn’t in the food either; everything they’d drunk or tasted has been analyzed. Everything, I tell you, was in order.” “What was it, then?” Sencort went at him, still with more impatience than interest. “Simultaneous, group indigestion?” “A poison, a definite, lethal agent, reached Costrelman and the butler--Swan--in fatal amount and the rest in less quantity. The post-mortem on Ed and Swan was completed this morning; there was definite, characteristic destruction of motor nerve centers.” “Characteristic of what?” This was old Sencort--yielding, pliable nature, he had, you see--at Teverson again. “A cheerful little chemical composition which the infernal-machine and poison squad of the secret service call KX.” “What?” “In your school days, how did you designate algebraically an unknown quantity?” Teverson asked old Sencort, evidently knowing that the way to handle the old boy was by going to the good old Socratic. “By the later letters of the alphabet,” Sencort grunted.