"Eddie," she said. "If you know anything, tell. Mitch just isn't worth any more trouble to us." "Tell what?" Ed demanded, rising. "About where Mitchell Prell is," Granger told him. "You said things which hinted that he might be around." Ed's throat tightened. It was still a minor shock to remember that the probe beam had probably been used on this house sporadically for years. The refined radar of the probe beam could, if minutely focused, make fair pictures of distant things inside walls. But Ed didn't think that it could make the small print on a sheet of letter paper readable. But there were instruments that could pick up faint sounds from miles away--a voice, for instance--and amplify them to audibility. Ed was still sure that, over distance, his mind itself remained inviolable. Ed felt cornered by the brute forces that always take over whenever reason is broken down by fear. Once his uncle had been a scapegoat to blame for disaster. Then, poor memories and triumphant years had half forgiven him. But now, during trouble, he was guilty again. And according to savage concepts of justice so were his relatives. The confusion of half blaming his uncle left Ed and was replaced by stubborn loyalty. He summoned all his self-control and grinned carefully. He wondered if the fright in Granger's large eyes reflected realization at last of the angry hands, gone completely untrustworthy, that now touched the controls of modern science. Was he getting intelligent so late? Or was he afraid of something simpler? Ed forced a laugh. "You picked up my muttering, Granger," he accused. "I wonder what _you_ mutter about, these days? Grant me the same privilege of nervousness under strain which you could do a lot to relieve, everywhere, as I have been begging you to see. No, I don't know where Mitchell Prell is, though I wish I did." The plain-clothes man had moved over to the table. Now he peered into the microscope. Soon he motioned to Granger to do likewise. Ed felt the roots of his hair puckering. "What does '_Nipper_' signify to you, Dukas?" Granger asked at last, levelly.