And thats why Im here, Bisesa said.

The acceleration was savage.

Edna and John saw nothing of the detonation, when it came, because all the Liberators sensors were shut off or turned aside, the flight deck windows opaque. Pressed back in her couch, fleeing the explosion, Edna was reminded of training simulations she had run of the suicidal missions of Cold War attack pilots, when you were expected to fly your FJ4-B Fury fighter aircraft into enemy territory at three hundred knots, release the nuclear weapon strapped to your belly, and get yourself out of there, trying to outrun a nuclear fireball, forcing the craft up to speeds the designers never intended. This mission now had something of that feeleven though, paradoxically, she was safer than any of those heroic, doomed 1960s pilots could ever have been. There were no shock waves to outrun in the vacuum of space; nuclear weapons actually did more damage in an atmosphere.

The acceleration cut out suddenly enough to throw Edna forward against her restraints. She heard John grunt. With a clatter of attitude thrusters the ship turned, and the windows cleared.

The fireball from the nuke had already dissipated.

And the Q-bomb, John briskly reported, is unaffected. Apparently unharmed. It hasnt deviated from its trajectory at all, as far as I can measure.

Thats absurd. It isnt that massive. Apparently something iswell, anchoring it in space more firmly than mere inertia. Edna, Libby called, Im prepared for pass four.

Edna sighed. There was no point backing down now; if nothing else they had made their hostile intentions absolutely clear to the Q-bomb. Proceed. Arm the fish.

Alexei said, Look, Bisesaif the Q-bomb is a Firstborn artifact, then we believe that the best way to combat the threat is to use the Firstborns own technology against them. This Eye is the only sample of that technology we have. And you may be our only way to unlock it.

As the conversation became more purposeful, Bisesa had the sense that something changed about the Eye above her. As if it shifted. Became more watchful. She heard a faint buzz on her comms link, and her suit seemed to shudder, as if buffeted by a breeze. A breeze?

Myra, frowning, tapped her helmet with a gloved hand. Yuri looked up. The Eyeoh shit Thirty seconds, said Libby.

John said, You know, theres no reason why the bomb has to be constrained by the range of action its shown so far. It could just swat this damn ship like a fly.

So it could, Edna said calmly. Check your constraints. John reflexively snapped down his pressure suit visor. Ready? Fire your damn fish, John muttered.

Edna tapped her final enable button. The A-drive cut in, and acceleration bit once more, driving them in their heavy suits back into their couches.

Four torpedoes were fired in a single broadside from cannon mounted on the Liberators hull. They were antimatter torpedoes, so unstable they had to be armed with their H-bar pellets in flight, rather than back in dry dock.

One detonated early, its magnetic containment failing.

The others went off simultaneously in a cluster around the Q-bomb, as planned.

The Q-bomb sailed on unperturbed. Mankinds most powerful weapons, delivered by its first and only space battleship, had not been able to scar the bombs hide, or dislodge it from its chosen trajectory by a fraction of a degree.

So thats that, Edna said. Libby, log it. While they waited for further orders from Achilles, the Liberator stood off at a safe distance from the Q-bomb, matching its trajectory.

Christ, John Metternes snapped, releasing his restraints. I need a drink. Another shower, and a bloody drink.

Mars dust and loose bits of ice were churning on the floor, whipping up to collide with the shining face of the Eye. Bisesa felt fear and exhilaration. Not again. Not again!

Myra ran clumsily to her mother, and grabbed her. Mum!

Its all right, Myra Her voice was drowned out in her own ears by a rising tone, a sweep up the frequency scale into inaudibility, loud enough to be painful.

Yuri studied a softscreen sewn into his sleeve. That signal was a frequency chirplike a test Ellie was laughing. It worked. The Eye is responding. By Sols light! I dont think I ever believed it. And I certainly didnt think it would work as soon as this woman walked into the Pit.

Alexei grinned fiercely, Believe it, baby!

Its changing, said Yuri, looking up.

The Eyes smooth reflective sheen now oscillated like the surface of a pool of mercury, waves and ripples chasing across its surface.

Then the surface collapsed, as if deflating. Bisesa found herself looking up into a funnel, walled with a silvery gold. The funnel seemed to be directly before her facebut she guessed that if she were to walk around the chamber, or climb above and below the Eye, she would see the same funnel shape, the walls of light drawing in toward its center.

She had seen this before, in the Temple of Marduk. This was not a funnel, no simple three-dimensional object, but a flaw in her reality.

Her suit said, I apologize for any inconvenience. However The suits voice cut out with a pop, to be replaced by silence. Suddenly her limbs turned flaccid and heavy. The suits systems had failed, even the servomotors.

The air was full of sparks now, all rushing toward the core of the imploded Eye.

Wrestling with her own suit, Myra pressed her helmet against Bisesas, and Bisesa heard her muffled cries. Mum, no! Youre not running out on me again!

Bisesa clung to her. Love, its all right, whatever happens... But there was a kind of wind, dragging at her. She staggered, their helmets lost contact, and she let go of Myra.

The storm of light grew to a blizzard. Bisesa looked up at the Eye. The light was streaming into its heart. In these final moments the Eye changed again. The funnel shape opened out into a straight-walled shaft that receded to infinitybut it was a shaft that defied perspective, for its walls did not diminish with distance, but stayed the same apparent size.

And the light washed down over her, filling her, searing away even her sense of self.

There was only one Eye, though it had many projections into space-time. And it had many functions.

One of those was to serve as a gate.

The gate opened. The gate closed. In a moment of time too short to be measured, space opened and turned on itself.

With a snap, it was over. The chamber was dark. The Eye was whole again, sleek and reflective in its ancient cage.

Bisesa was gone. Myra found herself on the floor, weighed down by a powerless suit. She yelled into the silence of her helmet. Mum. Mum!

There was a click, and a soft hum. A female voice said levelly, Myra. Dont be alarmed. I am speaking to you through your ident tattoo.

Whats happened?

Help is on its way. I have spoken to Paula on the surface. You two have the only ident tattoo. You must reassure the others.

Who are you? I suppose I am the leader of what your mother called this faction. I know your voice. From years agothe sunstorm My name is Athena.

25: INTERLUDE: A SIGNAL FROM EARTH.

2053.

In this system of a triple star, the world orbited far from the central fire. Rocky islands protruded from a glistening icescape, black dots in an ocean of white. And on one of those islands lay a network of wires and antennae, glimmering with frost. It was a listening post.

A radio pulse washed across the island, much attenuated by distance, like a ripple spreading across a pond. The listening post stirred, motivated by automatic responses; the signal was recorded, broken down, analyzed.

The signal had structure, a nested hierarchy of indices, pointers, and links. But one section of the data was different. Like the computer viruses from which it was remotely descended, it had self-organizing capabilities. The data sorted itself out, activated programs, analyzed the environment it found itself inand gradually became aware.

Aware, yes. There was a personality in this star-crossing data. No: three distinct personalities. So were conscious again, said Thales, stating the obvious.

Whoopee! What a ride! said Athena skittishly. Theres somebody watching us, said Aristotle.

Witness was the only name she had ever known.

Of course that didnt seem strange to her at first, in her early years. And nor did it seem strange that though there were plenty of adults in the waters around her, she was the only child. When you are young, you take everything for granted.

This was a watery world, not terribly unlike Earth. Even its day was only a little longer than Earths.

And the creatures here were Earthlike. In the bright waters of the world sea, Witness, a bundle of fur and fat something like a seal, swam and played and chased creatures not unlike fish. Witness even had two parents: having two sexes was a good strategy for mixing up hereditary material. Convergent evolution was a powerful force. But Witnesss body plan was based on six limbs, not four.

The best times of all were the days, one in four, when the icy lid of the ocean broke up, and the people came flopping out onto the island.

On land you were heavy, of course, and a lot less mobile. But Witness loved the sharp sensation of the gritty sand under her belly, and the crispness of the cold air. There were wonders on the island, cities and factories, temples and scientific establishments. And Witness loved the sky. She loved the stars that gleamed at nightand the three suns that shone in the day.

If this world was something like Earth, its sun was not. This system was dominated by a star twice as massive as the sun, and eight times as bright; it had a smaller companion barely noticeable in the giants glare, and there was a third, a distant dim red dwarf.

Across eleven light years, this system was easily bright enough to be seen from the Earth. This was Alpha Canis Minoris, also called Procyon. This star was known as a double to astronomers; that small second companion had never even been detected from Earth.

But Procyon had changed. And the living planet it had succored was dying.

As she grew older, Witness learned to ask questions.

Why am I alone? Why are there no others like me? Why is there nobody for me to play with?

Because we face a great tragedy, her father said. We all do. All over the world. It is the suns, Witness. There is something wrong with the suns.

The giant senior partner of Procyon, Procyon A, had once been a variable star.

When it was young it shined steadily. But the helium ash produced by the hydrogen-burning fusion reactor of its core slowly accumulated in its heart. Trapped heat lifted the helium layer, and all the immense weight of gas above: the star swelled, subtly, until the trapped heat could flood out, and the star collapsed once more. But then the helium trap formed again.

Thus the aging star became variable, swelling and collapsing over and again, with a period of a few days. And it was that grand stellar oscillation that had given this world its life.

Once, before Procyon had become variable, the planet had been something like Europa, moon of Jupiter: a salty ocean trapped under a permanent crust of ice. There had been life here, fueled by the inner heat and complex minerals that came bubbling up from the worlds core. But, locked in the watery dark, none of those forms had progressed greatly in intelligence.

The new pulsation had changed all that.

Every fourth day the ice breaks up into floes, Witnesss parents said. So you can get out of the sea. And we did. Our ancestors changed, so they could breathe in the air, so much more oxygen-rich than the seawater. And they learned to exploit the possibilities of the dry land. At first they just emerged so they could mate in peace, and shelter their young from the hungry mouths of the sea. But later Yes, yes, Witness said impatiently. She already knew the story. Tools, minds, civilization.

Yes. But you can see that we owe all we haveeven our mindsto the pulsation of the sun. We cant even breed in the water anymore; we need access to the land.

Witness prompted, And now And now, that pulsation has gone. Dwindled almost to nothing, said her father. And our world is dying, said her mother sadly.

Now there was no sunlight peak, no melting of the ice. The peoples machines kept some of the ice open. But without the mixing of the air caused by the pumping of the star, a layer of carbon dioxide was settling over the surface of the ocean.

After a few centuries the islands were becoming uninhabitable. We have become creatures of sea and land, Witnesss mother said. If we cant reach the land The implications, her father said, are clear. And there was only one possible response.

Unlike humans, Witnesss folk had never got as far as a space program. They had no way of fighting this catastrophe, as humans had built a shield to fend off the sunstorm. They had faced the horror of extinction.

But they would not accept it. We simply had less children, Witnesss mother said.

The generations of these folk were much briefer than humanitys. There had been time for this cull of numbers to slash the population until, by the time of Witnesss birth, there were only a few dozen of them left, in all the world, where once millions had swum.

You can see why we did it, her mother said. If a child never existed, it cant suffer. It wasnt so bad, she said desperately. For most of the generations you could still have one child. You still had love.

Her father said, But in the last generation Witness said blackly, In this last generation you have produced only me.

Witness was the last ever child to be born. And she had precious duties to fulfill.

Stars are simple beasts, her father told her. Oh, it took many generations for our astronomers to puzzle out the peculiar internal mechanism that made our giant sun breathe out and in. But puzzle it out they did. It was easy to see how the pulsing started. But no matter how contorted a model the theoreticians dreamed up they could never find a convincing way to make the stars pulsation stop.

Her parents allowed Witness to think that through.

Oh, she said. This was a deliberate act. Somebody did this. Witness was awed. Why? Why would anybody do such a terrible thing?

We dont know, her father said. We cant even guess. But we have been trying to find out. And thats where you come in.

Listening stations had been established on many of the planets islands. There were clusters of telescopes sensitive to optical light, radio waves, and other parts of the spectrum: there were neutrino detectors, there were gravity wave detectors, and a host of still more exotic artificial ears.

We want to know who has done this, said her father bitterly, and why. And so we listen. But now our time is done. Soon only you will remain...

And I am Witness.

Her parents clustered around her, stroking her belly and her six flippers as they had when she was a baby. Tend the machines, her father said. Listen. And watch us, the last of us, as we go into the dark.

You want me to suffer, Witness said bitterly. Thats really what this is about, isnt it? I will be the last of my kind, with no hope of procreation. All those who preceded me at least had that. You want me to take on all the terrible despair you spared those unborn. You want me to hurt, dont you?

Witnesss mother was very distressed. Oh, my child, if I could spare you this burden I would!

This made no difference to Witness, whose heart was hardening. Until their deaths, she struck back at her parents the only way she could, by shunning them.

But there came a day, at last, when she had been left alone. And then the signal from Earth arrived.

Aristotle, Thales, and Athena, refugee intelligences from Earth, learned how to speak to Witness. And they learned the fate of Witnesss kind.

Procyons pulsation had died away much too early for human astronomers to have observed it. But Aristotle and the others knew the same phenomenon had been seen in a still more famous star: Polaris, Alpha Ursae Minoris. A baffling decay of the north pole stars pulsing had begun around 1945.

But I am constant as the northern star, Aristotle said, Of whose true-fixd and resting quality / There is no fellow in the firmament. Shakespeare.

So much for Shakespeare! said Athena.

This is the work of the Firstborn. Thaless observation was obvious, but it was chilling even so. The three of them were the first minds from Earth to understand that the reach of the Firstborn stretched so far.

Aristotle said gravely, Witness, it must hurt very much to watch the end of your kind.

Witness had often tried to put it into words for herself. Any death was painful. But you were always consoled that life would go on, that death was part of a continuing process of renewal, an unending story. But extinction ended all the stories.

When I am gone, the Firstborns work will be complete.