He switched on his helmet-beam. The beam cut a pale swath ahead of him through the trees, among the ruined columns of concrete, the occasional heaps of rusted slag. He entered the ruins.

In their center he found the towers and installations. Great pillars laced with mesh scaffolding – still bright. Open tunnels from underground lay like black pools. Silent deserted tunnels. He peered down one, flashing his helmet beam into it. The tunnel went straight down, deep into the heart of the Earth. But it was empty.

Where had they gone? What had happened to them? Trent wandered around dully. Human beings had lived here, worked here, survived. They had come up to the surface. He could see the bore-nosed cars parked among the towers, now gray with the night snow. They had come up and then – gone.

Where?

He sat down in the shelter of a ruined column and flicked on his heater. His suit warmed up, a slow red glow that made him feel better. He examined his counter. The area was hot. If he intended to eat and drink he'd have to move on.

He was tired. Too damn tired to move on. He sat resting, hunched over in a heap, his helmet-beam lighting up a circle of gray snow ahead of him. Over him the snow fell silently. Presently he was covered, a gray lump sitting among the ruined concrete. As silent and unmoving as the towers and scaffolding around him.

He dozed. His heater hummed gently. Around him a wind came up, swirling the snow, blowing it up against him. He slid forward a little until his metal and plastic helmet came to rest against the concrete.

Towards midnight he woke up. He straightened, suddenly alert. Something – a noise. He listened.

Far off, a dull roaring.

Douglas in the car? No, not yet – not for another two days. He stood up, snow pouring off him. The roar was growing, getting louder. His heart began to hammer wildly. He peered around, his beam flashing through the night.

The ground shook, vibrating through him, rattling his almost empty oxygen tank. He gazed up at the sky – and gasped.

A glowing trail slashed over the sky, igniting the early morning darkness. A deep red, swelling each second. He watched it, open-mouthed.

Something was coming down – landing.

A rocket.

The long metal hull glittered in the morning sun. Men were working busily, loading supplies and equipment. Tunnel cars raced up and down, hauling material from the undersurface levels to the waiting ship. The men worked carefully and efficiently, each in his metal-and-plastic suit, in his carefully sealed lead-lined protection shield.

"How many back at your Mine?" Norris asked quietly.

"About thirty." Trent's eyes were on the ship. "Thirty-three, including all those out."

"Out?"

"Looking. Like me. A couple are on their way here. They should arrive soon. Late today or tomorrow."

Norris made some notes on his chart. "We can handle about fifteen with this load. We'll catch the rest next time. They can hold out another week?"

"Yes."

Norris eyed him curiously. "How did you find us? This is a long way from Pennsylvania. We're making our last stop. If you had come a couple days later…"

"Some runners sent me this way. They said you had gone they didn't know where."

Norris laughed. "We didn't know where either."

"You must be taking all this stuff some place. This ship. It's old, isn't it? Fixed up."

"Originally it was some kind of bomb. We located it and repaired it – worked on it from time to time. We weren't sure what we wanted to do. We're not sure yet. But we know we have to leave."

"Leave? Leave Earth?"

"Of course." Norris motioned him toward the ship. They made their way up the ramp to one of the hatches. Norris pointed back down. "Look down there – at the men loading."

The men were almost finished. The last cars were half empty, bringing up the final remains from underground. Books, records, pictures, artifacts – the remains of a culture. A multitude of representative objects, shot into the hold of the ship to be carried off, away from Earth. "Where?" Trent asked.

"To Mars for the time being. But we're not staying there. We'll probably go on out, towards the moons of Jupiter and Saturn. Ganymede may turn out to be something. If not Ganymede, one of the others. If worse comes to worst we can stay on Mars. It's pretty dry and barren but it's not radioactive."

"There's no chance here – no possibility of reclaiming the radioactive areas? If we could cool off Earth, neutralize the hot clouds and -"

"If we did that," Norris said, "they'd all die."

"They?"

"Rollers, runners, worms, toads, bugs, all the rest. The endless varieties of life. Countless forms adapted to this Earth – this hot Earth. These plants and animals use the radioactive metals. Essentially the new basis of life here is an assimilation of hot metallic salts. Salts which are utterly lethal to us."

"But even so -"

"Even so, it's not really our world."

"We're the true humans," Trent said.

"Not any more. Earth is alive, teeming with life. Growing wildly – in all directions. We're one form, an old form. To live here, we'd have to restore the old conditions, the old factors, the balance as it was three hundred and fifty years ago. A colossal job. And if we succeeded, if we managed to cool Earth, none of this would remain."

Norris pointed at the great brown forest. And beyond it, towards the south, at the beginning of the steaming jungle that continued all the way to the Straits of Magellan.

"In a way it's what we deserve. We brought the War. We changed Earth. Not destroyed – changed. Made it so different we can't live here any longer."

Norris indicated the lines of helmeted men. Men sheathed in lead, in heavy protection suits, covered with layers of metal and wiring, counters, oxygen tanks, shields, food pellets, filtered water. The men worked, sweated in their heavy suits. "See them? What do they resemble?"

A worker came up, gasping and panting. For a brief second he lifted his viewplate and took a hasty breath of air. He slammed his plate and nervously locked it in place. "Ready to go, sir. All loaded."

"Change of plan," Norris said. "We're going to wait until this man's companions get here. Their camp is breaking up. Another day won't make any difference."

"All right, sir." The worker pushed off, climbing back down to the surface, a weird figure in his heavy lead-lined suit and bulging helmet and intricate gear.

"We're visitors," Norris told him.

Trent flinched violently. "What?"

"Visitors on a strange planet. Look at us. Shielded suits and helmets, spacesuits – for exploring. We're a rocket-ship stopping at an alien world on which we can't survive. Stopping for a brief period to load up – and then take off again."

"Closed helmets," Trent said, in a strange voice.

"Closed helmets. Lead shields. Counters and special food and water. Look over there."

A small group of runners were standing together, gazing up in awe at the great gleaming ship. Off to the right, visible among the trees, was a runner village. Checker-board crops and animal pens and board houses.

"The natives," Norris said. "The inhabitants of the planet. They can breathe the air, drink the water, eat the plant-life. We can't. This is their planet – not ours. They can live here, build up a society."

"I hope we can come back."

"Back?"

"To visit – some time."

Norris smiled ruefully. "I hope so too. But we'll have to get permission from the inhabitants – permission to land." His eyes were bright with amusement – and, abruptly, pain. A sudden agony that gleamed out over everything else. "We'll have to ask them if it's all right. And they may say no. They may not want us."