Jo looked down at her friend, listened to her shallow, unhealthy breathing. She had seen too many deaths, knew too well just how easily a living, thinking being could be turned into a body, a nothing, an empty bag of chemicals.

'We've got to do something something.'

Jo felt the blood flow to her face. That had been her line, once, many years ago.

'Rowenna's right, Jo.' Julie, standing over them, still visibly shivering in the tropical heat.

Jo came to a decision. 'OK. Have you any idea where I might find these habilis habilis things?' things?'

'Habilines? Try by the mountain. They might use caves for shelter, especially in the heat of the day. And there might be a spring, a pool, something.' With a shock, Jo realised that Rowenna too was visibly shivering.

Jo took a step forward, looked around at the heat-rippled plain, at the rough, dark rocks around the base of the mountain.

Anything could be hiding there: leopards, lions or perhaps unknown aliens here to make sure that Hynes's mission was a success.

This was dangerous dangerous. She might not get back.

But on the other hand, if she didn't do it, she wasn't going to live until morning, and neither were the others.

She made herself remember the jungles of Spiridon, the Daleks cruising through the mist. Autons, faceless faces turning the corner Sea Devils, Xarax, deadly parasitic Axons. If she could cope with that, she could cope with a leopard or two.

She noticed that there was a backpack on the ground.

'I don't suppose you've got anything as old-fashioned as a mirror in there?'

'You mean you want to look your best to meet your great-great-great-great grandpa?' said Rowenna.

Jo had to smile. 'No. Signalling. Anything that will reflect sunlight will do.'

Julie unlaced the bag, scrabbled around inside it. 'Will this do?' she asked weakly holding out an electronic personal organiser. 'The screen's reflective.'

Jo tried it out: the screen caught the sunlight well enough. Angling the machine carefully, she could see the pale reflection from it on Rowenna's face in the shade of the thorn tree stump.

The woman squinted, looked around, then realised what was happening and waved at Jo.

'One flash everything's OK,' said Jo. 'Two I've found water. Or habilines, or something useful anyway. Three, I'm coming back. OK?'

'How many for "I'm being eaten by a lion"?' asked Rowenna, deadpan.

Jo didn't reply, just started walking.

The floor of the corridor sloped downward so steeply that Sam needed to keep a hand on the wall to maintain her balance. It was made from stone, great grey flags glittering with tiny crystals. There was a constant breeze blowing up the slope: it seemed to promise a door, an outside, a vast fresh field full of poppies and daisies.

But Sam knew it wasn't true. This was the TARDIS. There was no outside, just the wind, coming from nowhere and going nowhere.

She looked over her shoulder, to check that Kitig wasn't following her. She'd asked him not to; he'd promised that he wouldn't; and she was sure he'd keep his promise. But she still felt guilty. The Doctor had told her to stay put. He'd told her that the existence of the universe was at stake.

I'm only seventeen, thought Sam angrily. How does the Doctor expect me to cope with making decisions about the fate of entire universes?

The answer was, of course, that he didn't. He hadn't. He'd told her not to. And she was still doing it, because she was certain that he was wrong.

Had she stopped trusting the Doctor?

It seemed like it.

I just have to give Kitig's people a chance, she told herself. I took him on board. I couldn't just let him sit there, paralysed, and watch while the Doctor destroys everything in his life.

The passageway began to level out, and the breeze declined. The stone walls began to change, becoming whiter, smoother, the material changing without a clear break from stone to a substance that resembled plastic. Round depressions appeared in them she remembered that the Doctor had called them 'roundels'. Ahead there was a bright, even light.

She walked on, saw the angular white shape of the secondary TARDIS console. A clean white floor. The smell of plastic.

Sam walked to the console, looked around until she found a likely door control. A red lever almost begging to be pulled.

She pulled it.

The roundelled doors opened. Africa was outside.

In the main console room, Kitig watched the screen as Sam stepped through the doors. It hadn't been difficult to work out how to operate the alien machinery: the scanner control was a simple knob push in for outside view, pull out for inside view. No keypads here, no microcalipers. Kitig wondered how something so apparently simple could control the massive forces needed to travel through time.

He watched as the doors closed behind Sam, then changed to an outside view. He hadn't followed her, he told himself.

He'd just watched her go. And he wasn't going to follow her now: he was just going to use the same route.

Even so, he knew he was breaking the spirit of his promise to her.

But she had been right. He had a greater loyalty.

Kitig thought about Narunil, about Critil, Jontil, and Mritig playing in the garden, about the vast, quiet city around them, about the vast, quiet, civilised civilised world he had left behind. world he had left behind.

'I will save you,' he murmured aloud. 'I will save you all somehow. And then I will come home.'

CHAPTER 14.

'You really ought to think about letting me go.'

Hynes's smile was almost more terrible than the fact that Julie was dying, thought Rowenna. His confidence confidence.

'Why?' asked Rowenna, her speech thick in her dry throat. 'In case Jo doesn't come back and we die and leave you tied up to die from dehydration? I'd say that was fair, wouldn't you?' She gestured down at Julie, curled up asleep in the patchy shade of the alien tree, breathing heavily, her skin a blotchy red and crawling with flies.

Rowenna's own skin was beginning to darken, and her head felt like it was on fire. She wondered how much longer she could hold the gun, let alone stay upright in this awkward position. Her back hurt like hell.

How long had Jo been gone? A half-hour? An hour? It seemed like forever.

Suddenly she became aware of a movement behind Jacob.

A figure, walking through the grass.

'Jo?' she called.

Not Jo.

A man.

A young man wearing an extraordinary costume, as if he were at a party: a long, bronzy-green velvet jacket, light-grey cotton trousers, and a white shirt with a wing-tipped collar. On top of it all was a folding sun-hat, like something from South South Pacific Pacific, from which fell light-brown, shoulder-length hair. He was strolling along with his hands in his pockets, admiring the scenery, as if he was taking an afternoon constitutional.

He saw her, and he smiled. 'I should be careful with that thing if I were you.'

After a moment Rowenna realised he meant the gun. She was pointing it straight at him.

She lowered it, slowly. 'Sorry, but I have to keep an eye on him,' she explained, indicating Hynes. 'Now perhaps you could oblige me by explaining who you are and how you got here?' But she was already feeling a curious sense of relief, a sense that everything would be all right now.

The man repeated his charming smile. 'I should be asking you that,' he said. 'But I think I won't, at least not straight away. Your friend needs help first, don't you agree?'

Rowenna shut her eyes for a second, opened them again.

The guy was still there. Not a fever dream then.

He bent down over Julie, then reached into his pocket and produced a hypodermic syringe. Rowenna opened her mouth to object, and though the guy didn't look round, he must have heard her indrawn breath, because he said, 'Trust me. I'm a doctor.' He was fitting a white plastic cuff around Julie's arm.

' The The Doctor? Jo's friend?' Doctor? Jo's friend?'

He didn't look up. 'Yes. I used to be Jo's friend. You're Rowenna, aren't you?'

Rowenna nodded, wondering how he knew her name. She looked over her shoulder to check on Hynes. He was staring at the Doctor, his eyes almost popping out of their sockets, his face twisted into a grotesque expression of anger or fear or both.

If Hynes didn't like this guy, then chances were she should be liking him.

The Doctor was drawing blood from Julie's arm into the hypodermic. Lights flickered in the air in front of it, and Rowenna heard an inanimate but somehow soothing voice speaking. She made out the words 'virus' and 'fatal' but everything else was a chatter of incomprehensible medical-speak.

Advanced technology, thought Rowenna blearily. Jo had said he was from the future, or something.

'Can you save her?'

'I can hold off the virus,' muttered the Doctor. 'Standard antiviral. But no, it won't save her. The virus contains prions five different kinds. They're virtually indestructible, once they're in your system.'

Rowenna felt a wave of dizziness run over her as hope drained out of her system. 'You mean we're gonna die anyway?'

The Doctor didn't reply immediately. He stood up and began pacing around the trunk of the alien tree, glancing at it curiously. 'Chronon-wave asynchronous transmission. Didn't think anybody was still using that,' he muttered. 'Trouble is ' Suddenly his face brightened. 'Yes! That's it! Because to feed its organic nature it draws from the energy in our universe, it can only force a divergence in time, not rewrite it from the start. Therefore when it tries to force a new universe into creation it's borrowing energy from ours and that will create a rift! No wonder the vortex is unstable!'

'Doctor,' Rowena interjected, more concerned for herself and Julie than for the vortex at this precise moment, 'how long are we gonna live?'

The Doctor glanced at her. 'Oh, don't worry. Prions take a long time to kill. They have to change your brain chemistry.

Whoever designed this thing intended it to spread through the food chain. Anything that dies of this and gets eaten will pass the prions on to the scavenger. If that that gets eaten when it dies ' He stopped pacing, stared at the horizon, transfixed with anger. 'This could wipe out the whole mammalian population of the planet! Whoever did this didn't care about gets eaten when it dies ' He stopped pacing, stared at the horizon, transfixed with anger. 'This could wipe out the whole mammalian population of the planet! Whoever did this didn't care about anything anything ' '

Rowenna swallowed, felt her body shaking.

For the first time the Doctor seemed to notice her distress. He walked over, crouched down, put his hands on her shoulders, gently straightening her body to a more comfortable position against the thorn tree.

'It's OK, Rowenna,' he said.

She wondered again how he knew her name.

'You won't die yet. I promise you that. When we get back to the TARDIS I can give you something to rebalance your body chemistry. You'll live as long as you ever would have done. And Julie will too.'

He stood up, began pacing around the tree once more.

Rowenna noticed that Julie's eyes had opened, and the colour on her skin was better. She tried to shuffle over towards her friend, using her arms as levers, but tipped sideways and lay helpless on the ground.

'Dammit!'

To her surprise, Julie stood up, swayed, stretched, and then walked over to her. 'Who's he?' she asked, indicating the Doctor. Her voice was rusty with the after-effects of fever.

Rowenna bit back her pain. 'Jo's friend. The one that works miracles. You were dying dying a minute ago.' a minute ago.'

'I don't feel too good now.' Julie brushed some of the flies away from her face, then knelt down and pulled Rowenna upright again.

'Where's Hynes?' she asked.

'Hynes? I ' Julie moved aside, and Rowenna realised that their captive wasn't where he should be.

'Doctor!' she called. 'Hynes has gone!'

The Doctor wandered round the tree, looked around for a moment. 'Oh, don't worry,' he said. 'I shouldn't think he's gone far. There aren't many places to go at the moment.' He frowned. 'A shame. I was going to ask him what he knew about this virus.'

Rowenna almost laughed. 'I think that might just be why he didn't want to talk to you, Doctor.'

The Doctor gave her a serious look. 'Oh, he wasn't responsible. He looked insane to me.'

'He had an alien friend.'

'Well, yes, I'd guessed as much. Big fellow, a bit like a horse with arms?'

Rowenna did laugh this time, so much that she almost fell over again. 'That's the one!'

'Not here, is he?'

'I don't think so.' Rowenna was still laughing. 'I guess we'd have noticed him.'