"McIlvaine's story was that a few moments later there was a blinding flash just outside his window," continued Harrigan. "There was also a run of instantaneous fire from the window to his machine. When he had collected his wits sufficiently, he ran outside to look. There was nothing there but a kind of grayish dust in a little mound--as if, as he put it, 'somebody had cleaned out a vacuum bag'. He went back in and examined the space from the window to the machine; there were two thin lines of dust there, hardly perceptible, just as if something had been attached to the machine and led outside. "Now the obvious supposition is naturally that it was Richardson out there, and that the lines of dust from the window to the machine represented the wires he had attached to his microphone while McIlvaine was at Bixby's entertaining his other two cronies, but this is fact, not fiction, and the point of the episode is that Richardson disappeared from that night on." "You investigated, of course?" I asked. Harrigan nodded. "Quite a lot of us investigated. The police might have done better. There was a gang war on in Chicago just at that time, and Richardson was nobody with any connections. His nearest relatives weren't anxious about anything but what they might inherit; to tell the truth, his cronies at Bixby's were the only people who worried about him. McIlvaine as much as the rest of them. "Oh, they gave the old man a hard time, all right. They went through his house with a fine-toothed comb. They dug up his yard, his cellar, and generally put him through it, figuring he was a natural to hang a murder rap on. But there was just nothing to be found, and they couldn't manufacture evidence when there was nothing to show that McIlvaine ever knew that Richardson planned to have a little fun with him. "And no one had seen Richardson there. There was nothing but McIlvaine's word that he had heard what he said he heard. He needn't have volunteered that, but he did. After the police had finished with him, they wrote him off as a harmless nut. But the question of what happened to Richardson wasn't solved from that day to this." "People have been known to walk out of their lives," I said. "And never come back." "Oh, sometimes they do. Richardson didn't. Besides, if he walked out of his life here, he did so without more than the clothing he had on. So much was missing from his effects, nothing more." "And McIlvaine?" Harrigan smiled thinly. "He carried on. You couldn't expect him to do anything less. After all, he had worked most of his life trying to communicate with the worlds outside, and he had no intention of resigning his contact, no matter how much Richardson's disappearance upset him. For a while he believed that Guru had actually disintegrated Richardson; he offered that explanation, but by that time the dust had vanished, and he was laughed out of face. So he went back to the machine and Guru and the little excursions to Bixby's...."