Sam looked over her shoulder at the TARDIS. A re-entry vehicle? The Doctor was dissembling, she realised. Prevaricat-ing.

OK. Lying.

Which meant that he didn't trust the Tractites. Sam mentally revised the seriousness level of this situation to 3.5 on the Jones-Richter scale, and rising.

'Paratractis,' the horsy creature was telling the Doctor. It added a string of galactic coordinates.

The Doctor sat down. Suddenly. There was a squelching sound as the seat of his less-than perfectly tailored fancy-dress trousers hit the ground.

Sam looked at the Tractite. It looked back at her. The big eyes were strange: blue-red, filled with slowly moving streaks, like cloud belts on a planet seen from space. As she stared, the large eyes closed, with an audible flapping sound, like a single beat of a bird's wing. The smaller eyes opened. They were different, and, since they were positioned together at the front for binocular vision, they looked disconcertingly human.

'This is Earth, isn't it?' she said, holding the alien's gaze.

'Earth? I don't recall a planet with that name,' said the alien. 'Are you in the wrong sector, perhaps?'

The other Tractite spoke. 'It's cold here. I think you should come to Afarnis with us. It's dry and warm there, and we should be able to find you something to eat and drink. Your vehicle should be safe here, or we can ask someone to recover it later, should you wish.'

Warm, dry air drifted over from the skimmer, smelling of hay. It was tempting, thought Sam, but the Doctor had said they were in trouble.

'Umm Doctor?' she suggested. 'Hadn't we better get back to the... to our re-entry vehicle re-entry vehicle?'

The Doctor was still sitting on the ground. 'Yes, Sam,' he said. His voice sounded as leaden as the grey light over the swamp. 'We could. But there isn't anywhere to go. Not here.'

Sam decided that this wasn't a time for coolness games. 'So where's here?' she asked simply.

The Doctor didn't reply, just stared at the ground in front of his muddy shoes. Sam noticed that the ground itself wasn't muddy, here on the island, but consisted of a mattress of fallen reeds, pale yellow and quite dry.

She looked up, saw the Tractites talking softly to each other. Then the pilot stepped down from the craft on to the reed matting. It gave under his weight, with a squelching sound from the mud underneath.

Sam swallowed. The alien was big. At least as big as a shire horse, perhaps bigger. The exposed hair on his legs and lower body was short and well groomed, silver-grey and white mixed in large, neat dapples. His legs ended in split hooves, part-shod with what looked like black leather.

He knelt down in front of her, so that their heads were almost level. His clothes shifted on his back with a scrunching sound, like someone turning over in bed.

'My name is Kitig,' he said.

'Sam Jones,' responded Sam automatically.

Rather to her surprise, the huge being extended a three-fingered hand towards her. The arm was thick, well muscled, and covered in short white fur. Tentatively, Sam extended her own hand, wary of making the wrong move and causing offence.

But the alien simply grasped her hand: the flesh of the three fingers was dry, rough, hairless, like an elephant's trunk.

The Doctor stood up suddenly and took the Tractite's other hand, his face lighting into an extraordinary smile. 'On the other hand, the Tractites are a very civilised people, one of the nicest in the galaxy. So it isn't all bad news.'

He glanced sidelong at Sam, and his eyes flashed for a moment. She knew the look: do what I say, wait for the explanations when I've worked out what they are myself.

We'll see, she thought. You aren't so infallible.

The Doctor was speaking to the Tractite pilot. 'Thank you very much for your offer of help. We'd love to come along with you. Wouldn't we, Sam?'

'Uhh yes,' agreed Sam dutifully not that she had much choice, because the Doctor had already jumped forward on to the platform of the skimmer.

Sam stepped up after him. The warm, dry air enveloped her like a blanket. The flooring was carpeted, with a geometrical pattern in browns and yellows. It had a vaguely Roman look: she wondered for a moment if this was Earth in about 55 BC and the Tractites had been studying the local customs. But if so, where were the locals? She looked down from the skimmer, which was now rising slowly over the swampland, but all she could see were reeds and reeds and more reeds, gradually vanishing into the grey mist.

'I'd sit down if I were you,' said the Doctor. 'I don't think this thing has acceleration buffers.' He was sitting cross-legged, his back against the central pillar. Looking at it, Sam realised that it was a small tree, a black trunk topped by a neat crest of fernlike leaves. Well, fernlike except that they were orange. Sam walked over and grabbed the tree trunk, but remained standing. It couldn't be worse than a bus in the rush hour, and she wanted to see where she was going.

Kitig took the controls and the skimmer began to rise. Sam caught a glimpse of the TARDIS, a little blue box standing in the mud at the edge of the island of reeds. Then it was gone, and there was nothing but the marshland and the dull grey sky. The skimmer appeared to have some kind of force field around it-: there was no wind in Sam's face, and the air remained warm, scented softly of hay.

The second Tractite came across and knelt in front of them. This one was actually bigger than Kitig quite noticeably so and Sam decided, without really knowing why, that it was female.

The alien shook hands and introduced herself as Narunil.

'I can see you're travellers,' she said. 'Our species doesn't travel much off-planet as a rule. But I went to Tractis with my parents once. Have you been there at all?'

'Oh, yes, many times,' said the Doctor. 'Wonderful place. Top-notch hay one of the best places in the galaxy for it.

There was a restaurant on the Bror coast Deeg's Place, was it? Or Keeg's? Can you remember, Sam?'

'Not sure. Teeg's, perhaps?' said Sam. 'Creeg's? Weeg's? Bleeg's?'

She hadn't been to Tractis, and the Doctor knew that perfectly well. But if the Doctor had some reason for portraying her as a seasoned, competent traveller well, that was OK with her.

As long as he didn't land her in it.

'The Bror coast?' Narunil asked. 'On Tractis? I don't think I've heard of it. Is it in the north somewhere?'

The Doctor frowned. 'Never mind. What's in a name? It was all such a long time ago. I've been to so many places. Ah!

Look!' He bounced upright, sprinkling pieces of partly dried mud from his trousers, and pointed out over the marshland. 'Is that Afarnis?'

Sam followed the direction of the Doctor's gaze and saw a blue-grey hillside speckled with lights, bright against the cloud-smothered daylight, slowly emerging from the mist. The skimmer got closer, crossing a wide grey river, and Sam could see buildings: spherical, semitransparent, they seemed to flow into and around each other like a cloud of bubbles in water. Between them, Tractites were moving spots of colour on white stone paths. Some carried lamps, mounted over their backs on delicate wicker holders.

'It's only a small city,' Narunil said. 'Not much more than an observation point. But then, this is only a small, damp island.' This last statement was accompanied by a gentle snort, and Sam realised that it was probably intended to be self-deprecating but Sam felt a chill despite the warm air inside the skimmer's force field.

A small, damp island.

That sounded like Great Britain. And hadn't London once been a swamp? She looked over her shoulder, saw the river receding behind them, broad and peaceful. It was the right size for the Thames.

We are are on Earth, she thought. on Earth, she thought.

But we're not in time to stop the invasion. The invaders are already here.

The human race is extinct.

The Jones-Richter trouble rating began to climb. Exponentially.

CHAPTER 3.

Rowenna Michaels was talking to a man who had been dead for two and a half million years.

'What was it like back then?' she asked him. 'How did it feel to be you?'

The empty eyes of the skull stared back at her. She waited for them to blink, for the skull to speak, an oracle from the African plains, several orders of magnitude older than Delphi. But there was no movement, no answer to her question.

No answer from a fossil, thought Rowenna. Hardly a big surprise.

She reached out to touch the mottled brown and white surface, and tried to imagine that she could feel through the years and the changes brought about by the process of fossilisation to touch the mind that had worked inside.

Nothing. Only silence. Empty bone.

'Try asking her what she had for breakfast. You might get a reply on that one.'

Rowenna pushed her wheelchair back from the bench, saw her colleague Julie Sands looking in through the open door of the prefabricated hut they were using as a lab, her hands covered in the ochre dirt of the Kilgai Gorge.

'Do you have to bring food into everything?' asked Rowenna, grinning as she noticed the half-eaten Hershey bar stuck into the pocket of Julie's buff-coloured field jacket. 'I mean, don't you ever consider going on a diet?'

Julie stepped up into the lab, patted the flanks of her large, square-built body and gave Rowenna a mock-aggressive glare.

' "Diet" is a medieval term used in reference to a congress of religious and/or secular persons for the purpose of deciding policy, and is also used as the name for some modern parliaments,' she said. 'I'm not aware of any other meaning.'

Rowenna snorted. She gestured at the clutter of papers, fragmentary fossils, plaster casts, cables, lights, computer parts, and minor scientific instruments that occupied Julie's workbench and significant areas of the floor around it. 'Know any good medieval definitions of the word "tidy"?' she hinted.

Julie looked at the chaos around her. 'Umm no,' she admitted, then gestured vaguely at Rowenna's bench and the assembled skull. 'How's it going?'

'It isn't.' Rowenna gestured at the skull, then at the laptop computer where she was supposed to be making notes on the brain structure of Homo habilis Homo habilis, the extinct human ancestor of which the skull was a part. 'He isn't giving me any ideas. I want a talking one.'

Julie laughed. 'Well, I can't do that for you, but I did find something new this morning. Take a look at this.' She crossed the floor, carefully negotiating the clutter, and handed a small fragment of fossil bone to Rowenna.

Rowenna held the fragment, cradling it gently between finger and thumb. It was darker than the skull on the desk, but that meant little. The original bone had been replaced by sediment. The shape of the fragment, however, was true to the smallest visible detail.

It was about five centimetres by three, very slightly curved, with jagged edges and traces of some ridging on one side.

Rowenna turned the fragment over a few times, puzzled. It was too thin, too finely shaped, to belong to Homo habilis Homo habilis. It almost looked modern, like a piece of a Homo sapiens Homo sapiens skull. Of course, that was no reason why it shouldn't be fossilised skull. Of course, that was no reason why it shouldn't be fossilised skulls of Homo sap Homo sap could date back half a million years but the sediments where Julie had been looking were supposed to be a lot older than that. could date back half a million years but the sediments where Julie had been looking were supposed to be a lot older than that.

'Where did you find this?'

Julie met her eyes. 'Where do you think?'

'Not in the gorge, I'd say. Too recent.'

'In the gorge,' said Julie quietly. 'About a yard away from where we found your friend on the bench last year.' She gestured at the skull.

Rowenna looked at the fragment again. There were still bits and pieces of brownish dirt clinging to it, and fragments of a harder rock matrix. 'It must be some kind of freak a Homo habilis Homo habilis born with a thin skull.' born with a thin skull.'

'The curvature matches Homo sap Homo sap skulls,' observed Julie. She walked across the lab floor, began washing her hands at the sink. 'I think we've got something new.' skulls,' observed Julie. She walked across the lab floor, began washing her hands at the sink. 'I think we've got something new.'

Rowenna felt her heart begin to thump hard in her chest. A new species of hominid. It was more than possible. The entire fossil record for early hominids consisted of two skeletons, a few dozen complete or near-complete skulls, and iso-lated fragments of teeth and bones, such as the one she was holding in her hand. The things were just so damn rare rare. An entire species, two and a half million years old, missed from the catalogues yes. It could happen.

And me and Julie have discovered it, she thought. This could be the biggest thing since Donald Johanson and Lucy. And all discovered by a two-bit reconnaissance expedition with one lab hut and a crippled woman Sharp pains shot up Rowenna's back as damaged muscles tried to contract against the bones that had been shattered by an intruder's bullet two years before. She realised that her hands were gripping the frame of her wheelchair. Gripping too too hard, dammit. She took a deep breath, then another, then another. hard, dammit. She took a deep breath, then another, then another.

the kid was turning, turning, the gun in his hand, the gun

Too much tension is a killer, she reminded herself. You've got a job to do here, so concentrate on that, not the awards you might win afterwards.

'You OK?'

Rowenna looked up, saw Julie standing over her, watching her carefully, head slightly on one side.

'Fine,' she said. 'Just a bit of back pain.'

Trying to control her excitement, Rowenna rolled her wheelchair back up to the workbench, put the skull fragment down and picked up a brush to clean off some of the remaining dirt. It took a couple of minutes. When she was satisfied that everything remaining was fossil or rock, she carefully prised at the rock matrix with her fingers. A piece fell away, and she saw that there was an indentation in the skull.

She smiled, pleased with her discovery. Marks and indentations on skulls were often important. They gave clues to the lifestyle of the hominid, and often clues to the manner of its death. There might be tooth marks from predators, or perhaps scavengers; cracks and fissures caused by accidental damage; more rarely, blows from stone tools had been found, indicating that humans had practised murder, or at least some kind of killing, for more than a million years. This one was a simple tooth mark, probably a dog or a hyena to judge from the size and shape.

Julie was standing over her again, chewing at the Hershey bar. 'Well, what d'you reckon?' she asked in a muffled voice.

Rowenna looked up at Julie's face, then down at the skull fragment. 'We need to find some more pieces of this,' she said.

'And...' She hesitated, aware of the practical difficulties this would cause her friend, then thought: To hell with that. 'I want to go with you.'

Julie grinned. 'OK, let's get loaded up!'

The Land Rover jolted and jumped along the bed of the dry river, each lurch of the chassis sending waves of pain up Rowenna's spine. She clenched her fists against the rollbar bolted to the roof, trying to ignore the pain and the resentment that it brought back, the anger because I could have done this on my own before I was shot. Dammit I could have walked I could have done this on my own before I was shot. Dammit I could have walked down here down here 'Are you OK?' Julie's voice. 'Do you want me to stop?'

Rowenna realised that she'd closed her eyes, and felt her face screw up tight with the pain.

'I'm fine,' she forced herself to say. 'Just hurting a little, that's all.'

'We're nearly there,' said Julie. 'We can stop for a while '

'Just get get there,' snapped Rowenna. there,' snapped Rowenna.

Julie glanced across at her. 'Hey, cool it.'

Rowenna took a breath, forced herself to calm down. She was lucky lucky, she told herself. Lucky to be alive, after being shot through the spine. Lucky to be fit enough to go on this expedition. Lucky to have friends like Julie who were willing to take her along, despite her disability and the logistical problems it caused.

And she was extremely damn lucky to have made a good find on the third day out. A miraculous find. Maybe the best find for about a decade.

Time to stop bitching.