Wilmer and Hayes exchanged glances. "That's fine," Wilmer said, "but abstruse, wouldn't you say? What I'm getting at is, I want to see a practical demonstration." "Put up or shut up, eh?" Flinn said. "I'd rather call it an examining of credentials," the physicist countered. "All right. I don't see any connection between my work and nuclear physics, but what do you want me to do? First, though, I'd better explain that I might fail. I'm really just on the threshold." "Granted. So I'll make it easy. Suppose--" He looked over his shoulder, faced Flinn again, and continued in a low voice: "Suppose you tell me what the man at the far desk is thinking." Flinn glanced past the physicist at the stranger across the room. The man seemed completely unaware of the others. He was poring over some papers that were spread out upon the desk. Flinn focused his eyes upon the man's head. His mind was really too steeped in fatigue for this sort of thing, but it was a chance not to be missed, a chance to demonstrate his talents in the presence of a responsible scientist, so he willed himself into a gradually deepening concentration. His eyes seemed to go myopic, out of focus. A gray, ethereal haze came into his consciousness, like swirling smoke. _Easy?_ But presently a picture began to form, blurred at first, then fragmentary, then coming into identifiable clarity. Flinn held it for a moment, before snapping back into objective consciousness. He was grinning slightly as his eyes refocused and came to rest on Wilmer. "Well?" the physicist asked. "What's his name?" Flinn said. "Barnes. Robert Barnes." "Say, Bob!" Flinn called out. The smallish, partially bald man at the far desk looked up and swiveled around to face him. "Tell me something, Bob," Flinn went on. "Do you act that way with all women, or just blondes?" Barnes' placid face suddenly underwent a marvelous transformation. First he blushed furiously. Then his jaw dropped open and the high color began to drain away. He stared across the room, his face pallid. "My God!" he managed to blurt in a stricken voice. * * * * * There was dead silence in the room as Wilmer and Hayes looked from Barnes' shocked face to Flinn's smiling one. "I think it's obvious--" Hayes started to say. "Me, too," Wilmer agreed. He looked sharply at Flinn. "Can you tell what I'm thinking at this moment?" Flinn shrugged. "Not without a special effort, and I'm not going to make that effort unless I have to." The physicist sighed and his tanned face relaxed a little. He looked at Flinn with a new respect. "I guess I'd better put you in the picture." He reopened the folder and extracted several newspaper clippings. "What I'm about to divulge is so unbelievable that--well, I'd best break it to you gradually. You know my job. That fact and this tan--" he pointed to his face--"should give you an inkling of what I've been up to the last few weeks."