After he had been operating for a few years, there was no installation on the face of the earth that could be considered Nipe-proof for more than a few minutes. He struck when and where he wanted and took whatever he needed. It was manifestly impossible to guard against the Nipe, since no one knew what sort of loot might strike his fancy next, and there was therefore no way of knowing where or how he would hit next. Nor could he ever be found after one of his raids. They were plotted and followed out with diabolical accuracy and thoroughness. He struck, looted, and vanished. And wasn't seen again until his next strike. Colonel Mannheim, who had carefully puffed a cigar alight and smoked it thoughtfully during Stanton's recitation, dropped the remains of the cigar into an ash receptacle. "Accurate but incomplete," he said quietly. "You must have made some guesses." He looked from Bart Stanton to Dr. Farnsworth. "I'd like to hear them." Farnsworth finished off the last of his coffee. "We've talked about it," he admitted. "Although I must say the hypothesis Bart has come up with would never have occurred to me. I'm still not sure I credit it, but" ... he shrugged ... "I can't say that I disbelieve it, either." Mannheim turned his eyes back to Stanton. His silence was a question. "Logically, my theory mightn't hold much water," Stanton admitted. "But the evidence seems to be conclusive enough to me." He got up, went over to the coffee urn, and refilled his cup. "It seems incredible to me that the combined intelligence and organizational ability of the UN Government is incapable of finding anything out about one single alien, no matter how competent he may be," he said as he returned to his seat. "Somehow, somewhere, someone must have gotten a line on the Nipe. He must have a base for his operations, and someone should have found it by this time. "If there is such a base, then it must be possible to blast him out of it without resorting to the kind of work it took to produce--me. "I may be faster and more sensitive and stronger than the average man, but that doesn't mean that I have superhuman abilities to the extent that I can do in two or three years what the combined forces of the Government couldn't do in ten. Certainly you wouldn't rely too heavily on it. "And yet, apparently, you are. "To me that can only mean that you've got another ace up your sleeve. You _know_ we're going to get the Nipe before I die. You either have a sure way of tracing him or else you already know where he is. "Which is it?" Colonel Mannheim sighed. "We know where he is. We've known for six years." IV INTERLUDE The woman's eyes were filled with tears, for which the doctor was privately thankful. At least the original shock had worn off. "And there's nothing we can do? Nothing?" There was a slight catch in her voice.