Joe was beginning to get a little bit scared. What could he have that the strangers would want? Certainly not his bike, for it was worth only a few dollars and had just about seen the end of its years of usefulness. He laughed mentally at the fantastic thought that maybe they were after his science-fiction magazines. Then, what? They were approaching Joe's house now and his fear mounted steadily. His parents were gone, away at some social function, and they wouldn't return for three or four hours yet. There was nothing else to do, and so Joe, philosophically deciding to let fate take its course leaped from his bike and made a sudden dash for the shelter of the house. * * * * * Instantly they were after him, pounding across the dew-laden sod with all the agility and grace of a couple of rampaging hippopotamuses. Joe bounded through the front door and swung to snap the night-lock. At that moment, something grasped his mind in a firm, unrelenting grip. He no longer had any desire to resist the intruders and stood waiting for them to enter and make him prisoner. Quickly Harl and Kir-Um forced him into a chair and stared down at their victim with triumphant eyes. "So," Harl panted. "At last we shall learn the secret of Joe Carson, Earth's most amazing genius. Kir-Um, he is but a youth. I shudder at the thought of one so young possessing so much knowledge. Could it be that we have made a mistake?" Kir-Um looked up at Harl reprovingly. "Do Martians ever err?" he demanded. "No, this boy has a powerful, secret weapon and we must get it from him, at all costs. I can't understand you, Harl. It would seem as if you actually sympathize with these puny Earth people. The Councilor wouldn't like to hear that, Harl. I would hate to see my best friend put to death because he was too friendly with the enemy." "I'm not friendly with these Earthlings, Kir-Um," Harl hastily objected. "I merely think we should be cautious and not proceed at too fast a pace but what we shall be lured into some sort of death trap." "Well and good," Kir-Um nodded. "I believe we both realize our task calls for vigilance and a meticulous sifting of fact from fancy. That much goes unsaid. Conceding this genius is merely a boy, perhaps he is a child prodigy or, then again, he may have invented this weapon by accident. That is of little import, however. He has the weapon, we want it and we shall have it." Harl bowed humbly. "You are right again, Kir-Um. Your deductive powers constantly amaze me. Shall we begin the questioning?" Kir-Um wasted no time in preliminaries, but came right to the point. "Where is your secret weapon, boy?" he snapped. He spoke in his native Martian tongue, but the thought behind the words was quite clear in Joe Carson's receptive mind. Joe fumbled for words and finally answered: