"You ready to tell me a little more about why this matters so much? I mean, now that we're here..."

"Take a look out of the window again, Floyd. Take a look at Mars."

Auger told him about Mars. She told him about Silver Rain, and what it had done to that world.

Silver Rain was a weapon, cultivated during the last conflict between the Slashers and the Threshers from samples of the original rogue nanotechnological spore that had ended life on Earth. With deft, snide brilliance, the military scientists of the USNE-aided by defectors from the Polities, who supplied the necessary expertise in nanotech manipulation-had taken the excessively crude bludgeon of the original spore and honed it into something sharp and rather lovely, like a Samurai sword. Then they had seeded it into the thickening atmosphere of the partially terraformed Mars, the spore encased in myriad ceramic-jacketed ablative pellets, and it had sunk down to the surface, spreading across a vast footprint.

The Polities had never a.s.sumed that their enemy would use nanotechnology against them. It was the one thing that the Threshers abhorred above all else.

It therefore made an ideal weapon of surprise.

Silver Rain was very difficult to detect. The Polity specialists on Mars were expecting something much cruder, and consequently their nanotech filters were tuned to ignore something so fine, so cunning, so deadly. It infiltrated organisms quietly, initially doing no harm. Not just people and animals, but every living thing that the colonists had persuaded to survive on Mars. It slipped through seals and airlocks; through skin and cell membranes and the blood-brain barrier. Even the droves of nanotechnological mechanisms that the Slashers carried within their own bodies failed to recognise the intruder. It was that good; that precise.

And for days it did nothing except insinuate itself more thoroughly into the colonists' world. It seeped into the irrigation system and used the ca.n.a.ls to travel beyond the original infection footprint. It transmitted itself by means of physical contact between people and animals. It used the weather, riding the winds. It replicated itself, efficiently and systematically, but never consuming resources that would have drawn it to anyone's attention. People began to report that they were feeling a little under the weather, as if about to come down with a mild cold.

But no one in the Polities had come down with a cold in living memory...

The USNE battle planners had programmed Silver Rain to trigger on 28 July 2243. It was a coincidence that the day and the month happened to be shared with the events of the Nanocaust: the timing of the Silver Rain deployment had been dictated by strategic considerations elsewhere in the war. But once that coincidence became apparent, the generals saw no need to alter their plans. It would send a signal- subtle or otherwise-to the Polities. This is payback, it said. This is the price you pay for the harm your ideological ancestors did to Earth.

When the trigger was operated, every infected organism died in the same convulsive instant as the machines erupted, little time bombs crammed inside every living cell. Recording systems showed people stopping in mid-stride, mid-sentence, mid-thought. They fell to the ground, every biological event in their bodies aborted like a rogue computer process. They didn't bleed. They didn't even undergo any of the medically recognised phases of putrefaction. They just became a kind of dust, loosely organised into the shapes of corpses. When the cities and settlements began to fail, pressure-containment systems breaking down through lack of human maintenance, the corpses simply blew away like so many piles of ash.

It had never been the intention of the USNE to destroy all life on the planet: they had too many Martian interests of their own to go that far. Had Silver Rain slipped from their control (it had never been tested on such a scale before, and its effects were not entirely predictable), they would have deployed a counter-spore designed to neutralise the original weapon before it did excessive harm. But there was no need for that. The Silver Rain had worked exactly as advertised.

In the aftermath, the Slasher forces were paralysed by the scale of the atrocity. Sixty thousand people had died on Mars-more than the total number of casualties sustained in the conflict up to that point. But just when the Slashers were ready to launch a devastating counter-offensive against Tanglewood, using weapons that they had kept in reserve until then, there was an equally shocking turn of events amongst the Threshers. Senior officials denounced the actions of the battle planners who had developed and deployed Silver Rain. A moderately b.l.o.o.d.y coup followed, and those responsible for the crime against Mars were tried and executed. The punishments seemed to sate the Slashers. Within weeks, ceasefire terms had been agreed, with hostilities ending by late August. Mars returned to nominal Thresher control in 2244, but with significant concessions to the Slashers. While it was not exactly true to say that Mars had recovered from its a.s.sault, it had begun the healing process. The terraforming programme soldiered on, never getting any closer to its goal, but it was something to live for, regardless. Ambitious new settlements appeared in the Solis Planum and Terra Cimmeria regions, and the refurbishment of the high-orbit port, abandoned and mothballed during the war, brought a healthy dose of commerce.

But even now, after twenty-three years, the Scoured Zone was still lifeless. By accident or design, the gene-tweaked crops never took root there again. None of the settlements inside the Silver Rain footprint were ever reinhabited. They stood there now, half-buried in Martian dust: bone-white ghost towns, left exactly as they had been at the time of the atrocity.

Auger remembered her dream of Paris: the drummer boy on the Champs-Elysees.

"That was twenty-three years ago," she concluded. "Officially, the weapon doesn't exist anymore. Even the blueprints were supposed to have been destroyed. But Susan White didn't write those words on a postcard for nothing. Someone's got hold of it again. Maybe even improved it. And the next target isn't a few tens of thousands of Martian colonists. It's three billion people-the entire population of your version of Earth."

"But why?"

"To erase what should never have been. To wipe out those three billion lives as if they were rogue programs in some vast computer simulation. To turn back the clock to the moment of the quantum snapshot and obtain a pristine copy of the Earth, unenc.u.mbered by anything as messy as living, breathing inhabitants."

"It's monstrous," Floyd said, horrified.

"From one point of view. From another, it's simply a question of tidying up-like airbrushing a photograph. Remember what that war baby said in Berlin? All you really are to them is three billion dots."

"We have to stop this."

"And we're trying to. But we may be too late. If they already know the physical co-ordinates of the ALS, all they need to do now is to get there and deliver the Silver Rain-"

"Then we have to get there ahead of them."

"Nice in theory, Floyd. But we don't know where the ALS is. There's an awful lot of galaxy out there."

"Then we need to find out those co-ordinates as well. They must have smuggled them out, right?"

"Floyd, we're talking about three numbers. They don't even have to be big ones. No one needs to specify the position of the ALS to within a centimetre. It's like looking for an island in the Pacific Ocean. All you need is a grid reference accurate enough to rule out any other possibilities."

"Then we look for a grid reference."

"It could be anywhere, hidden in any form. It could be a telephone number, or something even less obvious."

"But those numbers must be somewhere. Could they have been hidden in the things Susan White was sending back home?"

"She was on our side, Floyd."

"I'm not saying that she knew what she was carrying, just that she might have been acting as a courier for the bad guys without ever realising it."

"It's still hopeless. Even if we knew for a fact that the numbers were in those papers...where would we start? The co-ordinates could be stored in the tiniest microdot, or in one telephone number amongst the thousands in the cla.s.sified adverts."

"All I'm saying is that we have to do something."

"I agree," she said, "but maybe our first priority ought to be getting rescued."

Something distracted her: a slight change in the quality of light flooding the cabin. They were still

tumbling, the Sun still flashing through the window once a rotation, but now there was a pinkish glow that stayed with them all the time, as if the transport was enveloped in its own little cloud of glowing light.

"You still think someone's going to pick us up?" Floyd asked.

"They're looking for us," Auger said.

"Even if the blowing up of that moon wasn't part of the plan?"

"Someone will still want to know what happened to us." But even as she said it, she felt her certainty

draining away. By its nature, the hyperweb portal was ultra-secret. Most of the people who knew anything about it would have been inside Phobos when the attack took it apart.

"Auger?"

"I think we may be in more trouble than I first thought. Aveling and Barton are dead. Apart from Niagara and Caliskan, I don't know who's left out there to look for us."

"Niagara and Caliskan?"

"Niagara's our Slasher mole, the man who fed us the know-how to make the Phobos link operational in the first place. Caliskan is the man who sent me to recover Susan's belongings. Niagara may have been inside Phobos when it was destroyed, but Caliskan's probably still in Tanglewood."

"Then we'd better hope he hasn't forgotten about you."

"Floyd, there's something not right about this." She closed her eyes, silencing a moan as the discomfort in her shoulder took on a sharper, nastier edge. "The more I think about it, the more I'm coming to believe that none of this was an accident."

"None of what?"

"The collapse of the wormhole. Granted, the whole thing was becoming increasingly unstable, but the

snake robot should have been able to compensate for that. It should have been able to manage a safe contraction of the throat."

"So what are you saying?"

"I think the robot was sent there to destroy the link."

"But the robot helped you."

"Yes," she said. "And it probably meant to save my life. I don't think it had any idea that it had been

tampered with. The sabotage order could have been buried deep beneath its surface programming."

The pink glow had intensified: fingers of light now licked around the armoured aperture of the window.

It still bothered Auger, but she wasn't sure why.

"Why would anyone want to sabotage the link, if that's the only way back to Paris?" Floyd asked.

"That's what worries me. Not just because it implies that someone within the organisation set out to

collapse the link, but also because it must mean that the Slashers no longer need it themselves."

"Why would they throw away something like that?"

"They wouldn't," Auger said. "Not unless they already had another way of reaching Paris."

"You mean they already have the co-ordinates of the ALS?"

"Either that, or they're very close to finding them out."

The thing that had been bothering Auger about that pink glow finally pushed its way to the front of her

pain-fogged mind. She felt herself go quite cold, even the stab of the wound no longer her most immediate concern. "Floyd, do something for me, will you? Climb up and take another look through the window."

"Why? You think someone else is out there?"

"Just do it." She watched him intently as he did as he was told.

"Now tell me what I'm supposed to be looking for."

"Tell me if Mars looks any bigger than the last time you saw it."

Floyd took a look and then stared back at her, light and shadow slipping over his face with clockwork

regularity. His expression told her everything she needed to know. "This isn't good, is it?" Floyd asked.

"Get back in your seat. Fast."

"What's wrong?"

"What's wrong is that we're not in orbit around Mars. If that planet looks bigger, it's because it's closer.

We're falling towards it. I think we're already skimming the upper atmosphere."

Floyd returned to his seat and lost no time in buckling up. "How do you know?"

"I didn't, for a while. I just had a bad feeling that it might turn out this way. Phobos was in orbit around

Mars, moving at exactly the right speed for its alt.i.tude. But we came out of the portal with our own velocity relative to the moon-hundreds of metres per second, at least. Whatever trajectory that put us in, it wasn't going to be the same one as Phobos. There's a chance we might have lucked out and had a boost in the right direction, away from Mars-"

"But today isn't our day for lucking out."

"No," she said. "Doesn't look as if it is. We came out at the wrong angle, at the wrong speed. We're hitting the atmosphere."

"And that's as bad as it sounds, right?"

"Ever wish upon a falling star, Floyd? Well, now's your big chance. You'll even get to be the star."

"What will happen?"

"What will happen is that we'll burn up and die. If we're lucky, we'll have been crushed unconscious by