He turned to Burl, who sat tingling with suspense. "You, Burl Denning, are apparently still carrying some sort of electronic or subelectronic charge which is attuned to the controls of the Sun-tap station. We feel that you should be along on this expedition. It will be long and dangerous, it will involve landings on worlds no man has ever visited or expected to visit for hundreds of years. There is an enemy in the sky who will certainly try to stop our single ship. To be bluntly honest, the voyagers on this ship face such dangers as explorers have not faced since the days of Magellan and Cook. Its chances of return are probably remote. But with the permission of your father, which he has already given, I would like to ask that you volunteer to join its crew." Burl felt dizzy, his heart thumping painfully within his chest. He took a deep breath, and then carefully, trying to keep his voice from quivering, he said, "Yes, I'll go." Chapter 4. _The Hidden Skyport_ Around the table there was a concerted sigh. Burl, his ears still throbbing from his sudden excitement, realized each of them had been holding his breath. General Shrove smiled and glanced at the elder Denning, who sat expressionless. It is not an easy thing for him, Burl thought. At that moment, Burl knew that he had come of age. This moment of decision, coming truly and literally like a bolt out of the blue, had thrust him into man's estate before his time. He would show that he was able to carry this burden. Shrove now spoke to Lockhart. "Colonel, we are holding you to your schedule. According to it, you can take off in five more days. Will you need any more time because of this addition to your crew?" The stocky air veteran shook his head. "Not at all. We'll be loaded and ready on the hour I set. I'll take Denning in hand and brief him on what he may need to know. Actually, we may even be able to get him a home-leave. After all, his duties won't begin until actual planetfalls are made." They rose from their seats. Burl stood up, uncertain as to procedure, but Lockhart came over to him and took his arm. "Burl, we're going to have to give you a rundown on the ship and the plans. We've no time to waste if you want to get a chance to say good-by to your folks later on." "I understand," said Burl. He turned and waved to his father, who was in conversation with the general. "I'll see you at home in a few days, Dad," he called, then followed Lockhart out. Outside the building they were joined by several other members of the conference and immediately ringed about by a squad of Air Force men wearing sidearms. Burl realized that they were to be thus guarded everywhere they went. Obviously, the possibility that the builders of the Sun-traps might have agents operating on Earth had occurred to the officers. Russell Clyde, the young astronomer, was among their group. He walked over to Burl and shoved out a hand. "Glad to have you with us, Burl. This is going to be quite a trip!"