The computer's owners had lost their grip on it somewhere in West Virginia, close to the border with Maryland. (Cobb had no information on where it might have been before that.) Somewhere in the countryside, apparently; although the emails were vague on this point, Swan guessed that a vehicle carrying the device had run off the road, and a local possibly a farmer had got hold of the pieces of the machine. There were five parts. Swan guessed input, storage, CPU, memory, output although if this really was a new kind of computer, the old architecture might have been irrelevant. Which parts had she and Luis bought?

The hypothetical farmer had looked to make a quick buck from his find. It hadn't been quick after all. Swan had long been familiar with the underground of collectors, spies, and suspicious types who traded in esoteric and forbidden technology, but of course the farmer had never heard of them.

His initial efforts to sell the components had got him nowhere.

It was almost two years before news of their existence trickled out to the grapevine.

Over the following months, a gaggle of collectors and suspicious types turned up, looking to beg, borrow, or steal the components. The farmer quickly realised that what he had given up on as junk had a real value. He played coy, pretending he had already sold some of the items, making sure that each customer only got one piece of the puzzle.

Swan was surprised when she put these events onto a timeline. The computer had fallen off the back of the truck, or what have you, in 1970! All this time, its bits had been out there, becoming more and more separated. Why had its owners waited so long to retrieve their property? The only explanation was that they simply hadn't known it was there.

When it fell off that truck, to them, it became invisible. That was a bit of luck for her imagined farmer. One of Cobb's pals hinted darkly that the owners had visited the original finder and they hadn't exactly brought him candy and flowers.

1970. Swan spun the chair back and forth, thinking. One h.e.l.l of a lot had happened in computer technology since then.

Could the components really still be valuable after all this time? The auctioneer had certainly thought so, and she had learned to trust his judgement. An awful lot of freaks and hobbyists thought so too they had pursued the components from one end of the country to the other.

That clinched it. If the technology was outdated and worthless, they'd never have bothered to come after it eleven years later. Perhaps losing it had stalled a research project, something truly revolutionary which could now continue.

More likely, the research had continued, and now there was a risk that the secrets of a new computer might be revealed if the early prototype was rea.s.sembled.

Swan closed her eyes for a few moments, ma.s.saging her eyelids. The picture of the thing in Luis's bathtub kept drifting into her mind.

Who were the original owners? It was a toss-up between a big corporation and a spy agency. Swan guessed the latter more likely to have the resources and the drive to find and recover the components, more likely to need to keep its technology dark.

They had already got three. One from California, where it had been undergoing testing in a Silicon Valley lab. As far as Swan could tell, the owners represented by 'River' had broken in and taken it. One had got as far as Arctic Canada; it had been bought back at an exorbitant price.

And then there was the component Chip Cobb had been hired to retrieve. Swan had met him once, and they had swapped a few emalls; he was a hub in the collectors'

grapevine, best known for his ability to get hold of information about prototype computers (and very occasionally, the prototypes themselves). The components would have been right up his alley. River had been talking to him in email, promising cash and circuit boards If he could locate the device. (Cobb had spent a lot of time trying to trace River's email connection. Only once had he been able to track his employer back to a pirated account at a defence contractor only to have River shut down that account and turn up again from a different direction. 'He seems to be everywhere and nowhere,' a frustrated Cobb had told a friend.) River was certain that the remaining three components had stayed on the east coast in fact, had probably not gone far from what he once called the 'crash site' (confirming Swan's theory that a secret transport had been involved). Although collectors were keen to get their hands on the devices, they eventually realised that they simply couldn't do anything with them. Swan recalled her own frustration with the loopy plastic ball. So they had moved slowly through the grapevine, sold at auction or in private transactions. But one of the three, discovered Cobb, had been sold only once from the original finder to an obsessive collector in Salisbury. The guy was famous for never playing with the toys he bought just shrinkwrapping them in plastic and locking them away in a vast array of filing cabinets in his bas.e.m.e.nt. Even if Cobb hadn't been able to trace the sale of the component to Salisbury, he might have guessed it had ended up in the black hole of the guy's collection.

Cobb's job was to wrest that component away from the guy in Salisbury. River provided a slush fund in four figures to help persuade the collector to give up the goods. Cobb had dealt with the man before; he knew the chances of prying the item away from his bosom were pretty low, especially once the collector realised it was valuable.

Over a period of six months always begging more funds from River he tried everything he could to win the component. He offered the collector all sorts of bribes and trades. He paid him a 'consultation fee' (large enough to make Swan whistle) just to whet his appet.i.te. When his patience started to run out, he switched his tactics. Small hints became minor hara.s.sment became outright threats. The collector found his phone disconnected and phone books for exotic countries delivered to his door, COD. His home number mutated daily, making it impossible to call him. Finally, Cobb hired a thug to break into the collector's bas.e.m.e.nt. The thug didn't even get close; the place was wired and armoured like the vault of a bank.

Cobb was astonished when River decided the best idea was to talk to the collector in person. His employer had somehow got it into his head that where greed and fear hadn't worked, simple honesty would. River would sit down with the man, explain everything, and the collector would be only too happy to hand over River's property.

Cobb had never seen River in the flesh. He turned out to be a bland-faced man in his thirties, wearing a dark suit and hat. He had a pet parrot which went with him everywhere. It was the only strange thing about him; everything else was entirely forgettable. In an email to a friend, just before it all went wrong, Cobb admitted he had trouble remembering what the man looked like.

River arrived early in the morning and knocked on the door until Cobb tumbled out of bed. The man was happy to sit in the living room, in the dark, while Cobb got a final couple of hours of sleep. When the sun had come up, they set out for Salisbury.

That was where Cobb's emails ended. The rest of the story Swan was able to piece together by breaking into the accounts of the people he had shared his secrets with, and reading their emails. One quoted an entire news article, which told her everything worth knowing about what happened next. The collector was dead. Cobb was dead. Even the parrot was dead.

Of the component and River, there was no sign.

On the long drive, the Doctor and I swapped travel stories, while he tinkered with whatever it was he was making.

When I was small, my family would stay in a caravan park in the country town of Parkes. Or was it Forbes? Or perhaps it was the small city of Dubbo, and my childhood memories are even vaguer than I thought. I must try to find an atlas with enough detail of the New South Welsh countryside to work it out.

Anyway, the point was that we would drive from Parkes to Forbes (or was it the other way around?). My father said that the two towns were exactly eleven miles apart; he would get the three of us to watch the odometer, counting down the miles.

But the biggest thrill was always the visit to the thirty-one flavours ice cream shop in the town of Orange. One flavour for each day of the month, a sign said. 'I remember we arrived in Orange late one night after a long day's drive. I bawled my eyes out because the shop was closed. I've been to Baskin Robbins, sure. But it's not the same thing.'

Peri said sleepily from the back seat, 'Did you ever see a horseshoe crab?'

'Ah, we don't have 'em Down Under.' As if on cue, that b.l.o.o.d.y song came on the radio. I flipped the dial impatiently.

'I did see a lot of jellyfish at Bateman's Bay, though. I could never understand the point of going on a beach holiday where it's too dangerous to swim. I saw a dogfish and a manta ray there, too. And a spider with orange legs that lowered itself in the back of the car and made my little brother scream.'

'We used to turn them over,' said Peri.

'What? Spiders?' I said.

'Horseshoe crabs. It was a game. You got fifteen points every time you found one on its back and turned it the right way up again. Maybe they're from s.p.a.ce.'

'Nonsense, Peri,' said the Doctor.

'They look like they're from s.p.a.ce.'

'The Cambrian Epoch may have been another world, but it wasn't another world. They're no more extraterrestrial than you are.'

'The ocean is just like outer s.p.a.ce.' She was murmuring now, half-asleep. I was suddenly reminded that she was only around half my age. Just a kid. 'One day all the weird creatures in there will come and invade us.'

'There are some people who believe this has already happened,' said the Doctor.

There was something about this silly conversation that was making the small hairs on the back of my neck stand up.

Maybe it was the image of the Earth as a little beach on the edge of an impossibly huge sea full of monsters. And these two travellers, the sorcerer and his apprentice, floating about on that cold sea in their little ship.

'You're like a horseshoe crab, aren't you?' said Peri. The Doctor glanced at me. 'Peri '

'I meant, a living fossil,' she said cheekily 'Go to sleep, Peri,' he told her. A few minutes later he said, 'Hmmph A living fossil indeed. In ten years' time in five five years' time the computers that are far beyond Peri's comprehension will be fossils themselves. People these days chuckle at the tiny brain of ENIAC. Soon they'll have a new joke every few years. And a new computer to buy. Perhaps future archaeologists will discover a layer of discarded personal computers all that's left of your young civilisation.' years' time the computers that are far beyond Peri's comprehension will be fossils themselves. People these days chuckle at the tiny brain of ENIAC. Soon they'll have a new joke every few years. And a new computer to buy. Perhaps future archaeologists will discover a layer of discarded personal computers all that's left of your young civilisation.'

'America's not doing too badly' I said. 'Sometimes you have to stick up for the Yanks. 'Not if they're producing technology at a rate like that.'

'Electronic digital computing is only one way of organising a civilisation,' said the Doctor. 'There are many other ways to manage information at high speeds much better ways. And besides, the human race has managed without any of them for most of its existence. Most human beings are still doing just that.'

I shrugged. 'I read somewhere that most people on Earth haven't even made a phone call.'

'That will remain true for a long time,' said the Doctor.

'But computers have a habit of getting in everywhere. Like the vermin that follow human beings as they stride around the Earth.'

'Computers are rats?'

'Perhaps a little more useful'

'I can't work out whether you like like them or not.' them or not.'

'As long as they're useful, I like them perfectly well.

When they start pretending to be people, that's another thing.'

He paused to consider. 'On the other hand, I've known some quite charming computers'

I had to grin. 'I'll bet you have.'

'Oh, good heavens.'

'What is it?'

'That sandwich Peri gave me. I'd forgotten all about it'

The Doctor extracted the cold and sodden melt from his pocket, sniffed at it, and then stuffed it into the glovebox. I watched out of the corner of my eye as he struggled with the contents of his pocket it seemed to be crammed with toys and coins and bits of junk, all of which needed wiping after their encounter with the sandwich. It was the equivalent of Mondy's bat-belt, an engineer's collection of tools and spare parts.

I was nodding to myself. The Doctor was obviously involved in the design of new computers which would make the current crop of high-tech gizmos look like junk not just faster machines, but machines with a completely different basis.

The Doctor seemed to guess my thoughts. 'Oh, I think the electronic digital computer has some life left in it yet,' he said.

'Electricity is quite a fast way to move information around. Of course, there are faster ways.'

'Like what?'

'Light, for example. You can't get faster than that.' I suppose he meant fibre-optic cables. 'Or if you must use physical things, then you keep making the components smaller and smaller to speed up the movement of information, you see until at last they are so small that quantum mechanics becomes a consideration.' He touched the back of my hand with a finger. 'Something like that already operates in your DNA.'

I shifted uncomfortably. 'That's enough about me. So where are you from?'

The Doctor raised an eyebrow at me. 'It's best not to know everything about a person. A little mystery is a good thing.' I couldn't interpret his smile.

We arrived in Ocean City not long afterwards. Peri sat up and peeked out through the venetians.

'Grim,' commented the Doctor.

'I don't know,' she said. 'I kind of like it.' Which made me wonder what kind of places she usually visited. 'It reminds me of being a kid. Do you think maybe when this is all over we could come back here?'

The Doctor hesitated. 'Perhaps in summer.' It was hard to imagine him on the miniature golf course, that was for sure.

'Maybe,' said Peri, in a small voice. I think they had both just remembered that they might not be together once this was all over. 'It'd be nice to just look around and not have to rush off because the planet's going to blow up.'

We parked several blocks from Cobb's house. The Doctor packed a dufflebag with equipment from the back of the RV: I could see the weight of it as he hefted it onto his shoulder. The machine he had built on our trip was inside, obviously. But what else had he stuffed in there? We followed him, Peri breaking into short bursts of running to keep up with his long stride.

The phone rang.

Swan froze at the sound. Literally froze, every inch of her skin turning blue-cold. The dead phone in the living room had come to life.

Years ago, Swan had seen an episode of some black-and-white anthology show, in which a phone junction box came to life and started calling people. Her younger self had been equal parts fascinated and frightened too scared to touch a phone for weeks, but secretly jealous of the monster and its power to mock the human voice. She had played its role many times since: the unseen, threatening caller, the voice which could be coming from the next room or from thousands of miles away. Now, for a second, she was that kid again, jumping every time she heard the phone ring.

Swan got up from the desk and stomped into the living room, furious with herself, ready to tear the ears off whoever was on the other end of that line. If it was some blundering telco technician, she was going to wish 'em into the cornfield.

Swan s.n.a.t.c.hed up the receiver and said nothing. After a moment, the Doctor said,'Ah, there you are. I'm afraid you beat us there after all.'

'You freakin' idiot,' said Swan. 'If you hadn't told me about Cobb, I'd never have come out here. What'd you think you were doing?'

The Doctor was silent for a long second. 'I a.s.sumed you knew one another.'

'Of course we knew one another. But he never mentioned anything about this.'

'Oh, good grief,' said the Doctor.

While they were arguing, Peri and I were marching up the street to Cobb's house. I was carrying the duffle bag, which wasn't light.

We both saw the veranda, and the office equipment inside, at the same moment.

'Stay back,' said Peri. She was tugging the Doctor's ramshackle device out of the bag. 'I'm gonna torch the porch.'

'You're going to do what?'

Peri hefted the long machine. 'Like this,' she said.

Fire erupted from the end of the thing with a heavy kerosene smell.

's.h.i.t!' I scuffled sideways like a startled dab.

The window burst inwards. Peri let go of the trigger for a second, startled. Then she got a crazy smile going and stepped up to it, pushed the blunt nozzle through, and pulled the trigger again.

'Jesus, girl, what are you doing?'

Peri started to turn towards me, making me jump back even further as the line of flame followed her motion. She realised and turned back to the window. 'Well, what does it look like I'm doing?' A pile of papers on Cobb's desk erupted with a crackling roar.

This time she held the trigger in, holding the Doctor's improvised flamethrower with both hands, moving it back and forth in quick little jabs. The desk erupted like a warzone in puffs of orange and black. The box of diskettes issued a hideous chemical smell as it began to melt and char.

The screen of Cobb's PC burst inwards with a terrific crunch. Peri yelped, jumping back and letting go of the flamethrower's trigger.

Swan dropped the phone the instant she heard the window go, knowing instantly that she'd been had. She ran back towards the study.

She reacted just as quickly when she saw the flames: she ran like h.e.l.l in the other direction, bursting out the front door of the house. We never even saw her, running like h.e.l.l from the back of the house.

She ended up watching from a couple of streets away as the fire engines rolled in. The trip hadn't been wasted; she knew far more than she did before. The ruse with the phone tap bad been worth it, although It meant she could never again use that method for disinformation. If the Doctor and co had arrived only a little earlier, she would never have had the chance to learn so much. But Cobb had never had the component at all, whatever he may have hinted to his fellow collectors.

California, Canada, Salisbury. The components she and Luis had bought were the only two left. Correction: the component Luis had hatched in his bathtub was the only component left. The Doctor was obviously playing the same role as Cobb had, acting as the original owner's agent. And she had let him take away something that was worth scouring the continent for, something that was worth killing for.

There was only one thing to do now The Doctor had watched until he was satisfied with the level of destruction; then he pulled a pair of miniature fire extinguishers out of the duffle bag and set about dousing the conflagration before it could spread further.

'As a matter of fact,' he a.s.sured me between cold bursts of white vapour, 'I called the fire brigade to warn them of my intentions just before we set to work. They're taking longer to arrive than I had expected. Perhaps they thought it was a prank call.'