Opening the tomb.

Stepping inside.

And up from the Valley of Kings, from Karnak and Luxor, winding with the Nile to Alexandria, a woman, ancient, wrists rouged and walking with legs numb in the grip of a gnawing, eating disease—

Nigel shook his head.

The steps were only markings. They led nowhere. He photographed them click whirr and moved on.

The odd humming, again. There was no air in here— how did he hear it? He coasted down a narrowing tube. The humming was stronger. Ahead loomed a sphere. It was not connected to the walls. Nigel touched it. It did not move. The humming increased. He stuck the adhesive webbing on the backs of his gloves to the sphere and used the leverage to swing himself around it. The space beyond yawned black. His torch licked into it and found nothing. The light simply faded away. Nothing was reflected back. The humming continued.

He moved to the far face of the sphere and peered into the abyss beyond. Nothing.

Abruptly the humming rose, shrieked, wailed—and stopped.

Nigel blinked, startled. Silence. Around him was a pocket of darkness. The sphere, when he turned to face it, seemed somehow inert, exhausted.

Nigel frowned. He jetted back to the sphere, worked his way around it and returned through the tunnel the way he had come, searching.

Three hours later, when he had exhausted his film canisters and was beginning to tire, he headed back. The network of corridors was a simple but space-saving web of spherical shells, intricately intersected, and he had no difficulty finding his way out.

“I’m back in the cabin,” he said, sighing with a leaden fatigue.

“My God, where have you been, Nigel? Hours without a peep—I was almost ready to come in after you.”

“There was rather a lot to see.”

“Houston’s patched through—and mad as hell, too— so start talking.”

He took them through it all, describing the small rooms with elaborate netting that might have been sleeping quarters, the places like auditoriums, the ceilings with dancing lights, all the similarities he could find.

And the strangeness: spaces clogged with an infinitely layered green film that did not dissipate into the vacuum around it, but rippled as he passed by; rooms that seemed to change their dimensions as he watched; a place that gave off shrill vibrations he felt through his suit.

“Was there any illumination?” Dave said.

“Nothing I could see.”

“We picked up a strong radio pulse several hours ago,” Dave said. “We guessed you were trying to transmit from inside.”

“No,” Nigel said. “I couldn’t raise Len or anything else on suit radio, so I packed it in and simply looked about.”

“The signal wasn’t on our assigned frequencies,” Len said.

“We missed recording it—only lasted a second or so, and all our monitoring is in the telemetry bands,” Dave said.

“Never mind,” Len said. “Look, Nigel, it’s just abandoned in there? No signs of occupants?”

Nigel paused. There were things he wanted to tell them, things he had felt. But how could he convey them? Earthside wanted facts.

Nigel had a sudden image of himself blundering ham-fisted through those strange stretching corridors. The sphere. That humming. Had he accidentally triggered something?

“Nigel?”

“I think it’s been vacant for a long time. There are big open vaults inside, hundreds of meters on a side. Something must have been in them—maybe water or food—”

“Or engines? Fuel?” Len said.

“Could be. Whatever it was, it’s gone. If it was liquid it probably evaporated when this vent opened.”

“Yes,” Dave said, “that could be what made the cometary plume, the Flare Tail.”

“I think it was. That, and the atmosphere that blew out through the crack. There’s a lot of disorder inside— things ripped off the walls, strewn around, some gouges in the corridors that could have been made by things flying by. I picked up some of the smaller stuff lying around and brought it out.”

No one said anything for a while. Nigel put a hand to the cabin wall near him, feeling the wholeness of it. He looked out at a burnished rock shelf and sensed the problem before him. It was something he could hold in one palm and turn to watch its facets catch the light, much as he had once seen in his mind Icarus slipping silently toward the Earth at thirty kilometers a second, himself and Len arcing out to meet the tumbling mountain, administer the kick, race home. That had been a clean problem with easy solutions, but now it crumpled and fell away from him, replaced by another, darker vision that slowly formed, coming to clarity in his mind—

Just before he had entered the dust plume, while Len was still in view, Nigel had taken a sighting on prominent stars to fix his inertial gyros. It was a simple process, easily done in the allotted time. Before swinging the telescope away from the port, a point of light caught Nigel’s eye and he focused on it. It swelled into a disk, blue and white and flat, and he realized that he was looking at Earth. A featureless circle, complete and serene. Alone. A target, unnoticing. Its smooth, certain curve seemed more than a blotch on a star background; no, it was the center. A hole through which light was pouring from the other side of the universe. Complete. He had looked at it for a long moment.

Through scratchy static, Dave said, “Well, we can give you the time for another trip inside, Nigel. Haul out everything you can, take some more photos. Then you and Len can rendezvous and get clear of the Egg and—”

“No.”

“What?”

“No. We’re not going to set off the Egg, are we, Len?” “Nigel—” Dave started, then paused.

“I don’t know,” Len said. “What have you got in mind?”

“Don’t you see that this changes everything?”

“I wonder,” Len said distantly. “We’re trying to save millions of lives, Nigel. When Icarus hits it’s going to wipe out a big chunk of territory, throw dirt into the air and probably change the climate. I kind of—”

“But it won’t! Not now, anyway. Don’t you see, Icarus is hollow. It has only a fraction of the mass we thought it did. Sure, it’ll make a pretty big blast when it gets to India, but nothing like the disaster we thought.”

Len said, “Maybe you’ve got something there.”

“I can estimate the volume of rock left—”

“Nigel, I’ve been talking to some people here at Houston. We started reevaluating the collision dynamics and trajectory when you found the core was hollow. We’ll have the results pretty soon, but until we do I just want to talk to you about this.” Dave paused.

“Go ahead.”

“Even if the mass of Icarus is a tenth of what we thought, its energy of impact will still be thousands of times larger than Krakatoa. Think of the people in Bengal.”

“What’s left of them, you mean,” Len said. “The famine cycles have killed millions already, and they’ve been migrating out of the impact area for over a year now. Since the Indian government broke down nobody knows how many souls we’re talking about, Dave.”

“That’s right. But if you don’t care about them, Len, think about the dust that will be thrown into the upper atmosphere. That might bring on another Ice Age alone.”

Nigel finished chewing on a bar of food concentrate. He felt a curious floating tiredness, his body relaxed and weak. The stimulants he had taken left him alert, but they could not wash away the lassitude that seeped through his arms and legs.

“I don’t want to kill them, Dave,” Nigel said. “Stop being melodramatic. But we’ve got to admit that what we can learn from this relic may be worth some human life.”

“What do you propose, huh? What jackass scheme have you got?”

“That we stay here for a week, ten days, stripping the inside of whatever we can. You fly us additional air and water—use one of the unmanned intercepts that’s carrying a warhead right now. We’ll get clear of Icarus in time for the other interceptors to home on it, and we’ll use the Egg, too.”