A shadow, unmistakable now, spread out over the stars: a hole in the sky, black as night, winged, purposeful. And, low toward the horizon, there was a flare of light.

"Lethe," said Nomi softly. "That was the GUTship. It's gone-just like that."

"Then we aren't going home." Hama felt numb; he seemed beyond shock. "... Help me. Oh, help me ..."

A form coalesced before them, a cloud of blocky pixels.

Kama made out a sketch of limbs, a face, an open, pleading mouth. It was Sarfi, and she wasn't in a protective suit. Her face was twisted in pain; she must be breaking all her consistency overrides to have projected herself to the surface like this.

Kama held out his gloved hands, driven by an impulse to hold her; but that, of course, was impossible.

"Please," she whispered, her voice a thin, badly-realized scratch. "It is Reth. He plans to kill Gemo."

Nomi set off down the ridge slope hi a bouncing low-G run.

Hama said to Sarfi, "Don't worry. We'll help your mother-"

Now he saw anger in that blurred, sketchy face. 'To Lethe with her! Save me ..."

The pixels dispersed into a meaningless cloud, and winked out.

Callisto reached the great tree.

The trunk soared upward, a pillar of rigid logic and history and consistency. She slapped its hide, its solidity giving her renewed confidence. And now there was no Night, no lurking monster, waiting up there to oppose her.

With purpose, ignoring the aches of her healing flesh and torn muscles, she began to climb.

As she rose above the trunk's lower tangle and encountered the merged and melded upper length, the search for crevices became more difficult, just as it had before. But she was immersed in the rhythm of the climb, and however high she rose there seemed to be pocks and ledges molded into the smooth surface of the trunk, sufficient to support her progress.

Soon she had far surpa.s.sed the heights she had reached that first time she had tried. The mist was thick here, and when she looked down the ground was already lost: the great trunk rose from blank emptiness, as if rooted in nothingness.

But she thought she could see shadows, moving along the trunk's perspective-dwindled immensity: the others from the beach, some of them at least, were following her on her unlikely adventure.

And still she climbed.

The trunk began to split into great arcing branches that pushed through the thick mist. She paused, breathing deeply. Some of the branches were thin, spindly limbs that dwindled away from the main trunk. But others were much more substantial, great highways that seemed anch.o.r.ed to the invisible sky.

She picked the most solid-looking of these upper branches, and continued her climb.

Impeded by her damaged arm, her progress was slow but steady. It was actually more difficult to make her way along this tipped-over branch than it had been to climb the vertical trunk. But she was able to find handholds, and places where she could wrap her limbs around the branch.

The mist thickened further until she could see nothing around her but this branch: no sky or ground, not even the rest of this great tree, as if nothing existed but herself and the climb, as if the branch came from the mist and finished in the mist, a strange smooth surface over which she must toil forever.

And then, without warning, she broke through the mist.

In a pit dug into the heart of Callisto, illuminated by a single hovering globe lamp, Gemo Cana lay on a flat, hard pallet, unmoving.

Her brother stood hunched over her, working at her face with gleaming equipment. "This won't hurt.

Close your eyes ..."

"Stop this!" Sarfi ran forward. She pushed her hands into Gemo's face, crying out as the pain of consistency violation pulsed through her.

Gemo turned, blindly. Hama saw that a silvery mask had been laid over her eyes, hugging the flesh there. "Sarfi? ..."

Nomi stepped forward, laser pistol poised. "Stop this obscenity."

Reth wore a mask of his own, a smaller cap that covered half his face; the exposed eye peered at them, hard, suspicious, calculating. "Don't try to stop us. You'll kill her if you try. Let us go, Hama Druz."

Nomi raised her pistol at his head.

But Hama touched the soldier's arm. "Not yet."

On her pallet, Gemo Cana turned her head blindly. She whispered, "There's so much you don't understand."

Hama snapped, "You'd better make us understand, Reth Cana, before I let Nomi here off the leash."

Reth paced back and forth. "Yes-technically, this is a kind of death. But not a single one of the pharaohs who pa.s.sed through here did it against his or her will."

Hama frowned. " 'Pa.s.sed through'?"

Reth stroked the metal clinging to Gemo's face; his sister toned her head in response. "The core technology is an interface to the brain via the optic nerve. In this way I can connect the quantum structures which encode human consciousness to the structures stored in the Callis...o...b..cteria- or rather, the structures which serve as, umm, a gateway to configuration s.p.a.ce ..."

Kama started to see it. "You're attempting to download human minds into your configuration s.p.a.ce."

Reth smiled. "It was not enough, you see, to study configuration s.p.a.ce at second-hand, through quantum structures embedded in these silent bacteria. The next step had to be direct apprehension by the human sensorium."

"The next step in what?"

"In our evolution, perhaps," Reth murmured. "With the help of the ax, we have banished death. Now we can break down the walls of this shadow theater we call reality." He eyed Kama. "This dismal pit is not a grave, but a gateway. And I am the gatekeeper."

Hama said tightly, "You destroy minds on the promise of afterlife-a promise concocted of theory and a sc.r.a.ping of cryptoendolith bacteria."

"Not a theory," Gemo whispered. "I have seen it."

Nomi grunted, "We don't have time for this."

But Hama asked, despite himself, "What was it like?"

It was, Gemo said, a vast, spreading landscape, under a towering sky; she had glimpsed a beach, a rising, oily sea, an immense mountain shrouded in mist...

Reth stalked back and forth, arms spread wide. "We remain human, Hama Druz. / cannot apprehend a multidimensional continuum. So I sought a metaphor. A human interface. A beach of reality dust. A sea of-entropy, chaos. The structures folded into the living things, the shape of the landscape, represent consistency-what we time-bound creatures apprehend as causality."

"And the rising sea-"

"The threat of the Xeelee," he said, smiling thinly. "The destruction to come. The obliteration of possibility. Even there, threats can reach ... but life, mind can persist.

"Configuration s.p.a.ce is real, Hama Druz. This isn't a new idea; Pleh-toh saw that, thousands of years

ago ... Ah, but you know nothing of Pleh-toh, do you?

The higher manifold always existed, you see, long before the coming of mankind, of life itself. All that has changed is that through the patient, blind growth of the Callis...o...b..cteria, I have found a way to reach it. And there, we can truly live forever -"

The ice floor shuddered, causing them to stagger.

Reth peered up the length of the shaft, smiling grimly. "Ah. Our visitors make their presence known.

Callisto is a small, hard, static world; it rings like a bell even at the fall of a footstep. And the footsteps of the Xeelee are heavy indeed ..."

Sarfi pushed forward again, hands twisting, agonized by her inability to touch and be touched. She said to Gemo, "Why do you have to die."

Gemo's voice was slow, sleepy; Hama wondered what sedative agents Reth had fed her. "You won't feel anything, Sarfi. It will be as if you never existed at all, as if all this pain never occurred. Won't that be better?"

The ground shuddered again, waves of energy from some remote Xeelee-induced explosion pulsing through Callisto's Patient ice, and the walls groaned, stressed.

Hama tried to imagine the black sea, the sharp-grained dust of the beach. Could it be true that Reth was accessing some meta-universe of theory and possibility-a place where every dust grain truly did represent an instant in this universe, a frozen slice of time, stars and galaxies and people and Xeelee and unfolding cosmos all embedded within?

But Hama had once visited the ocean-Earth's ocean- to oversee the reclamation of an abandoned ax sea farm. He remembered the stink of ozone, the taste of salt in the damp air. He had hated it.

Reth seemed to sense his thoughts. "Ah, but I forgot. You are creatures of the Conurbations, of the Extirpation. Of round-walled caverns and a landscape of gray dust. But this is how the Earth used to be, you see, before the ax unleashed their nanotech plague. No wonder you find the idea strange. But not us." He slipped his hand into his sister's. "For us, you see, it will be like coming home."

On the table, Gemo was convulsing, her mouth open, laced with drool.

Sarfi screamed, a thin wail that echoed from the high walls of the shaft. Once more she reached out to Gemo; once more her fluttering fingers pa.s.sed through Gemo's face, sparkling.

"Gemo Cana is a collaborator," Nomi said. "Hama, you're letting her escape justice."

Yes, Hama thought, surprised. Nomi, in her blunt way, had once more hit on the essence of the situation here. The pharaohs were the refugees now, and Reth's configuration s.p.a.ce-if it existed at all-might prove their ultimate bolt- hole. Gemo Cana was escaping, leaving behind the consequences of her work, for good or ill.

But did that justify killing her?

The pharaoh turned her head.

Sarfi was crying. "Mother, please. I'll die."

"Hush," said Gemo. "You can't die. You were never alive. Don't you see that? You will always be with me, Sarfi. In a way. In my heart." Her back arched.

"Oh ..."

Sarfi straightened and looked at her hands. The illusion of solidity was breaking down, Hama saw; pixels swarmed like fat, cubic insects, grudgingly cooperating to maintain the girl's form. Sarfi looked up at Hama with eyes like pits of darkness, and her voice was a flat, emotionless husk, devoid of intonation and character. "Help me."

Again Hama reached out to her; again he dropped his hands, the most basic of human instincts invalidated. "I'm sorry-"

"It hurts." Her face swarmed with pixels that erupted and evaporated from the crumbling surface of her skin. Now the pixels fled her body, as if evaporating; she was becoming tenuous, unstable.

Hama forced himself to meet her gaze. "It's all right," he murmured. "It will be over soon ..." On and on, meaningless endearments; but she gazed into his eyes, as if seeking refuge there.

For a last instant her face congealed, clearly, from the dispersing cloud. "Oh..." She reached up to him with a hand that was no more than a ma.s.s of diffuse light And then, with a silent implosion, her face crumbled, eyes closing.

Gemo shuddered once, and was still.

Hama could feel his heart pulse within him, the warm blood course. Nomi placed her strong hand on his shoulder, and he relished its fierce solidity.

Hama faced Reth. "You are monsters."

Reth smiled easily. "Gemo is beyond your mayfly reproach. And as for the Virtual child-you may learn, Hama Druz, if you pa.s.s beyond your current limitations, that the first thing to be eroded by time is sentiment."

Hama flared. "I will never be like you, pharaoh. Sarfi was no toy."

"But you still don't see it," Reth said evenly. "She is still olive-bat our timebound language can't describe it-she persists, somewhere out there, beyond the walls of our petty realization..."

Again the moon shuddered, and primordial ice groaned.

Reth murmured, "Callisto was not designed to take such hammer blows ... The situation is reduced, you see. Now there is only me."

"And me." Nomi raised the laser pistol.

"Is this what you want?" Reth asked of Hama. "To cut down centuries of endeavor with a bolt of light?"

Hama shook his head. "You really believe you can reach your configuration s.p.a.ce-that you can survive there?"

"But I have proof," Reth said. "You saw it."

"All I saw was a woman dying on a slab."

Reth glowered at him. "Hama Druz, make your decision."

Nomi aimed the laser pistol.

"Let him go," Hama said bitterly. "He has only contempt for mayfly justice anyhow."

Reth grinned and stepped back. "You may be a mayfly, but you have the beginnings of wisdom, Hama Druz."

"Yes," Hama said quietly. "Yes, I believe I do. Perhaps there is something there, some new realm of logic to be explored. But you, Reth, are blinded by your arrogance and your obsessions. Surely this new reality is nothing like the Earth of your childhood. And it will have little sympathy for your ambitions.

Perhaps whatever survives the download will have no resemblance to you. Perhaps you won't even remember who you were. What then?"

Reth's mask sparkled; he raised his hand to his face. He made for the pallet, to lie beside the cooling body of his sister. But he stumbled and fell before he got there.

Hama and Nomi watched, neither moving to help him.