The three got ready quickly. They donned their space suits, loaded the larger rocket plane with equipment, arms, and plenty of extra fuel. Just before they left, Lockhart gave them a word of caution. "Do not attempt to communicate with the _Magellan_ by radio. If Pluto is the Sun-tappers' home world, you may find yourselves surrounded by enemies, and overheard. Don't reveal our existence or position. If you have to talk to us, do not expect a reply unless it's an absolute emergency." Burl strapped himself into his seat within the rocket plane and glanced through the thick window. Below them was a world the size of Earth--a world which, if it had air and warmth, could most nearly be Earth's twin of all the planets in the system. This rocket plane had touched on the hot surface of Mercury, the first planet, In a little while it would set down on the frigid surface of the last planet. They had come a long way. Chapter 17. _Stronghold of the Lost Planet_ With a jolt that shoved the three men back in their seats, the rocket plane pushed out the cargo hatch, and slid into the dark of space on its own power. Behind them, the metallic surface of the _Magellan_ gleamed briefly, and then swung away on its orbit. Riding the red fire of their rockets, they headed on a long low dive for the mysterious surface below. Pluto was a vast hemisphere, half lighted in the faint, dim glow of the tiny Sun, half in the total darkness of outer space. Here and there wound a silent, frozen river of glistening white. They passed over a gulf of some frigid sea of liquid gases, from which islands of subzero rock projected, and moved inland over a continent of lifeless grays and blacks. Haines gently drew the ship lower and lower, and at last the rocket plane bumped to the ground. It rolled a few yards and stopped. The three men crowded to the door, tightened their face plates, and forced open the exit. There was a rush of air as the ship exhausted its atmosphere. Then, one by one, they stepped onto the bleak surface of the Sun's farthest planet. "I feel peculiar," whispered Burl. "This planet reminds me of something." "I have the feeling I've been here before," Russ said slowly. Burl felt an odd chill. "Yes, that's it!" Haines grumbled. "I know what you mean. I can make a guess. We've never really been the right weight since we left Earth. Even under acceleration there were differences one way or the other. But I feel now exactly as I did on Earth. That's what gives you the odd sensation of return." The two younger men realized Haines was right. For the first time since they had left their home world, they were on a planet whose gravity was normal to them. It felt good and yet it felt--in these fearful surroundings--disconcerting. Above them was the familiar black, unyielding sky of outer space. No breath of air moved. Yet somehow the scene resembled Earth. "It's like a black-and-white photo of a Terrestrial landscape," said Burl.