The beam from Petries helmet lamp shook from side to side. 'Ill never get into that.

Freya was looking up the river. 'Douse your light. Quickly.

The first time it might have been an illusion, but not the second. Far upstream, torchlight had reflected briefly off the swirling waves of the Styx.

33.

Rapunzel Bull was taking time off for the Iraqi crisis and she had three hours at the most.

There was a harsh cry and she almost jumped with fright. A large, long-legged pink bird with a yellow head fluttered past at eye-level and settled on a palm frond about six feet away, eyeing her curiously. Hazel Baxendale began to wonder if the Baltimore aquarium, even in the depths of the Baltimore winter, had been such a good idea.

She stepped carefully past the bird and carried on through a winding path, surrounded by lush greenery. An emerald-green iguana blocked her way. She moved respectfully past it and, a little further on, sat down on a wooden bench.

The tropical house was hot. And humid. Hazel draped her synthetic fur coat over the back of the bench, but kept her sungla.s.ses on. She waited.

The MIT engineer, Professor Gene Killman, was first to arrive. He was overweight, bald, with a gaudy yellow tie and dark gla.s.ses. He was licking his thin lips nervously, and looking around. He was almost comically furtive. The Presidents Science Adviser rubbed her forehead in despair and groaned inwardly. The man spotted her, looked around again, and sidled up to the bench, sitting down without once looking at her.

Something rustled in a tree. A small creature with long golden fur peered at them. 'What the h.e.l.l is that? she said.

'They call it a tamarin, maam. Cute, isnt it? So many have been taken for pets that its now an endangered species.

The Harvard philosopher, a small, cheerful, grey-haired woman in her forties, appeared a few minutes later and sat down on the other side of Hazel. The woman was dressed for the winter, in a heavy coat and scarf. It was ninety degrees hot and ninety per cent humid, but the philosopher kept her winter clothes wrapped round her. Just looking at her put the Science Adviser in a sweat.

Hazel said, 'Rosa Clements, meet Gene Killman. There was an exchange of cautious nods. 'Id like to emphasise again that this discussion is off-the-record and highly confidential. You wont understand whats behind it and all I can tell you is that it involves a matter of national security. Dont tell a living soul that Ive approached you for advice, not even your partners. Especially not your partners.

'Im between wives, Gene Killman volunteered.

'You have my full attention, maam, said Rosa Clements.

'Okay, here we go. Im going to ask three questions and I need the best answers going. You mustnt go jumping to any G.o.ddam conclusions; treat them as hypothetical. Number one. Is there life beyond the Earth? Or are we just a mega-fluke? Professor Killman.

The MIT man replied. 'In my opinion the Universe is teeming with life.

'I thought the odds against life forming by chance from simple molecules were super-astronomical. There are more ways to combine amino acids than there are atoms in the Universe, but only one way forms them into proteins.

'Thats a problem, Killman admitted. 'I dont have the answer except to say here we are, and life got established down here just as soon as the meteorites stopped smashing our crust. Take a walk over Slave Province in Canada and youre walking over micro-organic sediments a hundred feet thick and two and a half billion years old. In bits of West Greenland youre walking over iron-rich layers just as thick but four billion years old laid down by primitive microbes. If life was some sort of mega-fluke, how come were here and how come it got started so early?

'But what about intelligent life? Ive been told thats a quadrillion to one chance.

Killman said, 'Again, as soon as the conditions were right on Earth, there was a transition from single-celled life forms to multi-celled ones. Once youve done that, there are selective advantages all the way from the formation of nerves, then synapses, then cerebral ganglions and all the way to brains, intelligence and societies.

Hazel studied the man closely through her dark gla.s.ses. 'Are you saying intelligent life should be common out there?

'It should be everywhere.

'So why dont we see it everywhere?

'Thats a problem too, Killman admitted frankly. 'There have been lots of suggestions but I dont believe any of them.

But Hazel had stopped listening. The message had come home loud and clear: ET is on the cards.

'Okay. She sensed that something was slithering in a branch above her. 'Question number two. Say we receive an intelligent signal from s.p.a.ce. Say that all sorts of information, including genetic recipes to improve ourselves and our children, is in this message. Thats all the information you have to work on. I need the answers to the following questions. What sort of creatures would send it? What are we dealing with? Could it be on the level, or some sort of trap?

'Ms Baxendale, at MIT weve developed a doll. We call her Rapunzel on account of her long hair. She uses sensors to pick up movement and sound. She feels heat and she has a sense of touch. We have a couple of hundred facial expressions programmed into her and a few billion sound combinations. Would you believe she has moods? That she needs attention? Rapunzel can fool a child into believing shes a real baby.

'Call me Hazel. Whats your point, Gene?

'This, maam. Rapunzel is just a dumb machine made of plastic and wire, programmed by a few silicon chips. Were still in the steam age. Killman leaned forward. His voice was beginning to carry a zealous edge. 'But give it fifty years. A hundred at the outside. By then well have molecular and even quantum computers a billion times faster than anything on the market today. Well have dolls that fool adults, not just kids. Theyll be more mobile, smarter, and more imaginative than us. Were moving into the age of intelligent machines.

'But theyre still just machines. They cant think.

'Maam, Im a machine and I can think. What am I but a collection of atoms, every last one obeying the laws of physics? Same as the doll.

'So a hundred years down the line well have robot slaves. I still dont see what youre driving at.

'Hazel, these slaves as you call them will be smarter than us. A lot smarter.

Hazel Baxendale peered into the MIT mans eyes. 'Rapunzel will take over?

'As surely as night follows day. It goes further than smart robots, maam. Well have so many implants to boost us, neural circuits inside our heads, networked into grids, that well be hybrids ourselves. The need to outstrip rival nations or even just rivals will drive this. Eventually the carbon-based part of us will be redundant. Organic life carbon-based is on the way out. This is inevitable whenever intelligence develops technology. Sooner or later the technology takes over, supplants the primitive organic life. Therefore the signal this make-believe signal hasnt come from a life form like us. Its been sent by a machine.

Hazel puffed out her cheeks. She took a few seconds to a.s.similate this amazing new thought. 'Humanity will disappear?

The MIT engineer was scrutinising her. 'Itll merge with our smart machines. Not that there has been a signal, maam.

Hazel blessed her upbringing with three brothers on a Montana farm: her poker face was impenetrable.

Rosa Clements broke the silence. 'I think I can antic.i.p.ate your third question, maam.

'Go ahead.

'You want to know what would motivate a machine to contact us. More to the point, whether it would go by a moral code and if so, would that code be malign.

This is one bright cookie, Hazel thought with some alarm. 'As we keep telling each other, this is all hypothetical, she said. 'But if it wasnt, Id say this goes far beyond anything any Administration has ever had to handle.

Rosa nodded. 'You know what Truman said when he became President? He said, "There must be a million men better qualified than me to take on this job."

'Truman was wrong, Professor Clements. The American people didnt elect a million highfliers, they elected Harry S. Truman. Its the only qualification that counts.

The woman acknowledged the rebuke with a slight bow.

Killman stabbed the air with a fat finger. 'We couldnt relate to machine aliens. Theres no reason to a.s.sume theyd have anything like human compa.s.sion built into them. Theyd be programmed only to survive. Any philanthropy, any knowledge being fired at us, could be a mask. Theres no way to tell whats really lying behind it. So dont take a chance, dont respond. Dont even use the genetic recipes. There might be something hidden in them. He added, 'But as you say, this is all hypothetical.

Rosa smiled and said, 'Hazel, this is the sort of ill-informed rubbish technocrats come away with from time to time. They think because they can make machines that are brighter than humans, therefore these machines are conscious beings. The technocrats dont begin to grasp the subtleties. Will their dolls feel pain? No. Will they be conscious? No. Theyll never be more than mechanical zombies. I would say that no machine is ever motivated by philanthropy or malice or anything else. It just obeys a program. Any signal comes from a thinking, feeling intelligence. Or its proxy in the form of a tape recorder. Whatever, there will be an underlying moral code from a living creature. Intelligent machines will share the values of their creators. And these values will be benign.

Benign? It was the crucial issue. 'Convince me.

'As soon as h.o.m.o sapiens acquired intelligence we also got the concept of sin in other words, a sense of right and wrong. The ability to make moral decisions emerged along with intelligence.

'Tell that to the victims of the Hitler gang, or the Bin Laden creeps, Hazel said.

'Sure theres moral failure everywhere you look. But thats because were just out of the caves. Already we help others because we instinctively feel its the right thing to do, even if its of no advantage to us. A few thousand years down the line and itll be so ingrained in us we wont know any other way to behave. Okay were still apes, but cultural evolution is directing us towards a complete moral altruism. The signallers must have arrived there long ago.

'So moral capacity comes with the central nervous system. I buy that, Rosa, I really do. But what morality? How can you be sure the signallers have the same moral outlook as us?

'Because of ruthless Darwinian evolution. It works on societies. And thats why I believe the signal this make-believe signal is motivated by a genuine wish to help.

Hazel looked bewildered. 'Youre losing me.

'Its simple. In Nature you have survival of the fittest. In a primitive tooth and claw society you have the same. But as technology progresses it makes the killer instinct so destructive that you eventually have survival of n.o.body at all, except maybe a few cave men. Either evolution weeds out the killer instinct or everyone ends up dead. Either moral evolution goes hand in hand with technological evolution or were doomed.

Hazel was saying, 'You mean, the meek will inherit the Galaxy?

'Precisely. What wed get from the signallers would reflect the moral altruism theyd evolved into.

It was precisely the answer Hazel had been praying for. She stood up. Her head was dizzy with unfamiliar concepts, or maybe it was just the jungle heat after Camp David. The pink bird flapped its wings and took off to a safe height.

'Would you like to visit the sharks, maam?

'Id have loved to, Gene, while you tried to persuade me that the human race is about to let itself be obliterated by a clever doll, and Rosa here told me that if it speaks and acts like a human to the nth degree its still just a doll with no feelings and no consciousness. But I have to get back. Hazel Baxendale gave a lopsided smile. 'Im swimming with bigger sharks.

34.

Wormhole Freyas upper half disappeared, followed by her soaking jeans and finally her boots. A little cascade of rock dust sparkled briefly in Petries lamplight.

He took a last look at the Styx. The river had definitely risen, and its thundering was louder, but it was the lights which attracted his attention.

Two of them.

No, three.

Petrie switched off his helmet lamp, his feet wedged against the Madonna. He was breathing heavily and aware of his heart thumping in his chest.

Four. Moving in single file.

And now he was seeing black silhouettes, moving swiftly along the pathway: wild dogs hunting.

Five of them.

Six. Seven. They must be deploying the lot.

Petrie stopped counting. His mouth dry with fear, he edged himself towards the entrance, on his knees, seeing by Freyas receding lamplight. A final glance: eight, at a minimum. He forced himself into the crack, his breath noisy in the confined s.p.a.ce.

Freya was out of sight. There were three entrances, none of them more than two feet high. He kept his lamp off and sure enough, light was scattering from the wall of the left-hand tunnel.

On to his elbows. Petrie had never caved in his life. He quickly found himself sweating with exertion.

The light from Freyas lamp was getting fainter. Of course. She was smaller, slimmer.

Along the phreatic tube to a high vertical chimney.

How far along? He experimented with different ways of crawling but none of them seemed any better than the others. Freyas light was becoming a flicker, sometimes seen, sometimes not. He turned his own lamp on; the sight of the rock enclosing him accentuated his claustrophobia. He wanted to scream and push the walls away.

What the h.e.l.l is a phreatic tube anyway? It sounds Greek, he thought, trying to keep the panic demons out of his mind. Maybe to do with frenetic? Frantic? It made sense; the tube was round, as if it had been formed by water under pressure.

Water under pressure. Petrie thought about the melting snow half a mile overhead, percolating down through a million cracks and fissures in the limestone mountain. He wanted out of the phreatic tube more than he had ever wanted anything.

He pushed himself harder, fearful of losing his way in a subterranean labyrinth, of dying of cold and exhaustion, of stumbling into the enemy. After about five minutes, the roar of the Styx had vanished. The scrabbling of his boots and his own gasping breath cut into an unnatural silence, tomb-like.

The tunnel wall was closing in on him. A million tons of overhead rock were settling down. He was an insect, about to be crushed under the boot of the ancient Tatras. He found himself taking big, gulping, frightened breaths. The demons were now inside his brain, poking, grinning, gibbering.

Cut it out!

Twenty minutes into the climb, the tunnel was opening up and acquiring a steep upward slope. At last! A high vertical shaft: Tysons chimney.

He looked up, gasping with exertion. The chimney was a narrow, smooth-sided shaft. It rose almost vertically and it was higher, much higher, than he had visualised from Svetlanas sketch. He could barely make out the top with his torchlight. Water was trickling down its walls. And there was no sign of Freya, no light reflecting from her lamp.

He scrambled up a vertical face and then eased his head into the shaft. There would be no room to spread arms in the chimney, and he switched off his lamp. He inched himself up by holding himself in place with his elbows, bending his legs and thrusting against the shaft wall with his feet. A spray of cold water kept him soaked.

He slithered, lost about six feet, sc.r.a.ped his face, twisted his wrist, cursed aloud. After some minutes the chimney broadened marginally and he was able to grip its sides with icy fingers. He clambered up quickly, the iron taste of blood on his lip. There was a ridge; he waved his hands in the dark and found he could now hoist himself into a crouching position. He switched on his light and looked around.

He had reached a little chamber: the grotto, its floor covered with the white flowstone, a congealed river of rock. Three narrow tunnels led into it, discounting the one he had climbed up.

Freya, where are you?

Petrie remembered Svetlanas scribbled sketch. He now had to take the left-hand tunnel. He wriggled into it, crawled frantically along. It rose gently but he was making good progress. The tunnel was dry, but it smelled of damp and ancient air. The cold was intense now, into his bones, and Petrie thought it might be slowing him down mentally.

A long, narrow crawl, she had said.

A right turn and the tunnel narrowed to a mouth-shaped channel three feet wide and six inches high. Petrie stared. This wasnt in the map.

Stay calm.

Back out, inching painfully; now the demons were attacking in force, claustrophobia washing over him like big waves. Back into the little grotto with the flowstone, half-expecting soldiers. He switched off his lamp once more.

Pitch black. Not just any pitch black, like a country lane on a dark night. Pitch black somewhere inside a mountain; and lost.