They all stood in silence for a while, as the Doctor pulled the lever. Sam heard the dematerialisation noise as if from a long way away, and watched the TARDIS ceiling swirl and coalesce just like a sky-sea into the familiar pattern of the vortex. That faded too to be replaced by the usual dark-blue expanse.

Sam realised that she was crying.

The floor beneath her was juddering slightly, making it difficult to keep her balance. The effects of the wormhole? She imagined it wrapped round the heart of the TARDIS like a boa constrictor.

'How long till we're back on Earth?' she asked the Doctor, brushing away her tears.

'A few minutes,' he said, pacing up and down. 'I've just realised now that the Dominion is no more, there's nothing for the other end of the wormhole to latch on to. Look!'

They looked. Above her the TARDIS ceiling was a schematic, showing a golden line leading to Earth.

Fitz scratched his stubbly chin. 'Won't it just, well, close?'

The Doctor shook his head, ran his hands through his hair. 'No no no, there'll be ma.s.sive feedback, probably enough to destroy the TARDIS and and the Earth.' the Earth.'

Sam's stomach turned to lead a familiar feeling. The End of the World. Again.

'We can stop it, right?' said Fitz. 'Doctor?'

'I hope so,' said the Doctor. He went over to the console and slid something out, putting it casually into his waistcoat pocket. 'You know, all this time I thought the cause of the Blight was the wormhole. Instead it seems that Nagle's meddling has enabled me to save the T'hiili.'

'Hang on,' said Fitz. 'If the wormhole didn't cause the Blight, what did?'

'Well, you see,' said the Doctor, gripping the lapels of his frock coat, 'our universe is continually expanding, drawing energy from outside itself.'

'But there's nothing outside the universe,' said Kerstin incredulously.

'Not quite,' said the Doctor, wagging a finger at her. 'Our universe takes its energy from pocket universes, drawing the energy through black holes or Charged Vacuum Emboitements.'

'And that's what the Dominion is?' said Sam. It all sounded so clinical. 'A pocket universe? But it was inhabited!'

The Doctor looked away.

She went up to him. 'Don't avoid this, Doctor!'

He looked over at her. With that look. 'Sam.'

She refused to be taken in. 'I know you're going to say that there was nothing we could have done about it, but that doesn't make it right.'

A hand on her shoulder. Fitz. 'No one's saying it's right.'

'What the T'hiili called the Blight,' said the Doctor, pointing up at the ceiling, 'was the very edge of the universe; or rather, the process of energy conversion.'

How was she going to explain this to Itharquell? That the Dominion, his universe, his home, was destroyed consumed by hers? Sam turned away. She heard Fitz's voice as if from a great distance.

'Doctor, could we have stopped it? I mean, if we had found it in time?'

Stupid git. How could you stop the universe from expanding?

The Doctor's voice echoed her thoughts. 'No, Fitz. Not even the Guardians have that power.'

She heard Fitz swear, and met his gaze. There was anger in his eyes, too. Between them, they'd been involved in the battle to save the Dominion. They'd failed; and worse, there had never been any chance of success. It had all been for nothing. If the Doctor hadn't turned up at the last minute as always they wouldn't even be here.

'Still, it's not all doom and gloom,' said the Doctor. 'We saved the T'hiili. He gave her a hopeful little smile. Trying to appease her. Oh, she knew he wasn't to blame. She knew he had saved them all.

But she somehow didn't feel like giving him an easy ride. 'There were other races in the Dominion. It was an entire universe, Doctor. Imagine the billions of different races we didn't save.'

'The Ruin,' said Fitz, rushing up to the console. 'I almost b.l.o.o.d.y forgot. They've gone through the node they'll be on Earth now!'

The Doctor glared at him. 'That's the least of our problems. They'll die before they can cause much damage.'

'What about the people from Strangnas?' said Kerstin suddenly. 'The ones who were abducted when all this started?'

Sam remembered the body she'd seen, floating in the sky-sea, covered in purple growths. She decided to keep quiet about it.

The Doctor put his arm around Kerstin. 'They're lost, I'm afraid. They might not even have ended up in the Dominion the wormhole had many offshoots.' He smiled at Kerstin. 'Luckily for you, you ended up in the bit that's ensnared in the TARDIS.' He frowned, putting his hand on his hips. 'Or maybe it wasn't luck if it wasn't for you I'd never have got into the TARDIS.'

The Doctor walked up to the console, an indulgent smile on his face. 'What are you up to, old thing?'

As if in answer, the TARDIS lurched, and Sam grabbed hold of a nearby girder.

'Hold on said the Doctor, over an escalating electronic whine. 'This is it crunch time.'

Again, thought Sam wearily, bracing herself.

The Queen was lying on the side of a hill, one hand supporting her head, her red hair arranged around her. Itharquell knelt before her, scarcely able to believe that they had survived. They had been rescued. They were... here.

Itharquell looked up at the sky-sea above them. It was very pale blue, like the eyelids of a sleeping child. He stroked the ground. Strands of green protruded from it, soft and damp. Insects flew in the sweet air, like airborne breathing-sacs, only smaller, more colourful.

All around, the surviving T'vorha lay sleeping.

Was this all? All that remained of the T'hiili?

His gaze fell once more upon the Queen. No. That was not all. Within her, a whole new clutch of eggs. A whole new generation that he had seeded. Soon, she would change. Now, though, she was beautiful, and Itharquell drank in her beauty in rapt silence.

Suddenly the Queen gave a little cry, like a child. She slumped, her head falling into her lap.

Itharquell knew. It was over. The Blight had consumed the Dominion. There was nothing left. Where would they go now?

Major Wolstencroft approached the Ruin, treading softly on the forest floor, machine gun at the ready. Schofield was a few metres to his left, also approaching the creature. It had been standing there for over ten minutes, occasionally squirting a clear fluid from its lower trunk. When they'd come upon it, Schofield had wanted to shoot it but Wolstencroft had ordered him to observe. He wanted to see what it was doing. If it moved to attack them, they would fire.

But it hadn't moved.

And now it toppled, its legs giving way beneath it, the orange rubbery body folding, a strange hissing sound coming from the twin trunks.

'There you are,' said Wolstencroft, walking up to it. 'They are dying. That's why they're going back to the node they've realised that they can't exist on Earth, so '

Schofield pulled Wolstencroft back as the creature reared up, heaving itself forward, its uppermost trunk lancing out from the bell-like body. It had a surprisingly long reach and Wolstencroft staggered back. He fired a short burst and the trunk dropped to the ground, writhing like a dying snake. A black spike protruded from the end, whitish fluid dribbling from it.

'Remember what happened to the local lad who came back, sir,' said Schofield.

Wolstencroft turned away. The boy had been infected with alien eggs. He remembered Lindgard telling him about it, with ghoulish enthusiasm.

'It fancied you, sir,' said Schofield, smirking.

For once, Wolstencroft did not appreciate the private's humour. 'Shut up!' he said, bringing his machine gun to bear on the dead Ruin. 'Alien filth,' he growled, letting of a burst of fire into the dead body.

His anger spent, he turned away. Schofield was looking away, embarra.s.sed. Well, he was young, idealistic. Hadn't seen the terrible things Wolstencroft had seen. The mutations, the madness. One day, Schofield would see it all, too. And then he'd become as dedicated to protecting the planet as Wolstencroft was.

'Come on, lad,' he said. 'We're going back to the node. Make sure those b.a.s.t.a.r.ds get home.'

They set off through the forest, towards the distant white glow.

Sam clung to the girder, her teeth chattering, her vision blurring. This was one of the most traumatic landings she had experienced. It was as though the TARDIS were a Ventolin in the hands of a wheezy giant. Fitz and Kerstin were clinging to each other, stumbling over towards the library. The Doctor was at the console, total concentration on every line and angle of his face, seemingly oblivious to the chaos around him.

Sam kept her eyes on the blue fingers of the time rotor, though all she could see of them was a blur. Once the blur began to slow, it would almost be over. Hold on. Just hold on. Just don't think of the wormhole and what it was doing to the guts of the TARDIS. And her own guts, come to think of it. Her stomach felt as though it had come loose inside her body.

After what seemed like an age, the juddering began to ease off, and the blue fingers came into focus. Sam put her feet back on the floor. The Doctor ran around the console and yanked the chain that pulled the monitor down from its cubby-hole. Sam could see the screen clearly: earth scandinavia humanian era 1999 ad The Doctor gave a shout of triumph.

Sam let go of the girder and slumped to the floor.

Professor Nagle sat with her back against a tree, gently tending her wounded feet. Her tights were ripped and there were cuts all over her legs. Her feet throbbed with pain. She felt sick and tired and miserable and stupid and the Doctor had clearly left them all to stew.

Nagle closed her eyes. This was getting her nowhere.

She stood up, supporting herself against the tree, looking into the distance. The Ruin all seemed to have gone. Where, she did not know or care. Perhaps Wolstencroft had finished them all off; perhaps they had died naturally. Whatever.

The pain wasn't too bad, really. She stumbled through the forest, back towards the node. She could see it clearly deep within the forest, a glowing white wall, the light filtering through the branches, just as if the sun had fallen to Earth.

She had to go back. She gave a short, harsh laugh. The criminal returning to the scene of the crime. Perhaps she should throw herself into the node, see where it took her. Into the next world, if there was one. How many people had died because of her project?

No, don't think of that. Your aims and objectives were pure. You wanted to make things better.

But the roll call of the dead ran through her mind, unstoppable. The five locals who went missing she'd never even bothered to find out their names she'd never even bothered to find out their names and the one who came back, Johan Svensson. The farmer, Bjorn something. Boris Lindgard. How many of Wolstencroft's UNIT troops? All of them? Was Wolstencroft himself dead? The tears ran freely from her eyes as she recalled the past few years, the rivalry between herself and Wolstencroft. The 'I'm in charge no, and the one who came back, Johan Svensson. The farmer, Bjorn something. Boris Lindgard. How many of Wolstencroft's UNIT troops? All of them? Was Wolstencroft himself dead? The tears ran freely from her eyes as she recalled the past few years, the rivalry between herself and Wolstencroft. The 'I'm in charge no, I'm I'm in charge' stupid macho bulls.h.i.t. It had all been a game to her. in charge' stupid macho bulls.h.i.t. It had all been a game to her.

She was very close to the node now. She was amazed how quiet it was. Here and there, bodies of dead Ruin lay strewn, their legs tangled, their orange bodies deflated. She shuddered so much like dead spiders. However alien and horrible, they counted among the dead she was responsible for as well.

Oh yeah, and the entire human race, gobbled up by the wormhole. That was to come, of course. There was no stopping it now. What had the Doctor said? 'You've raised a dragon you cannot feed'?

She stopped, a few metres away from the node. It was a solid white wall, reaching so high into the sky that she couldn't see the end of it. Its edge advanced towards her, consuming all in its way.

She felt a deadness where her heart should be. Hard to breathe. Her feet hurt. She'd just stand here, wait for the end of the world. Feed the dragon she'd raised.

Professor Jennifer Nagle closed her eyes, lifted her face upward. The glow of the node showed as a pulsing red beneath her eyelids. 'I'm sorry,' she whispered. She didn't know what else to say. 'So sorry. I'm sorry. I'm so sorry, sorry, sorry '

Then everything went dark.

Sam got to her feet, rubbing her arms where they had chafed the girder.

Kerstin and Fitz were untangling themselves from a pile of books which had toppled over on to them.

Sam staggered over to the console. 'Is it over?'

The Doctor nodded. 'Almost. Bringing the TARDIS back here has sealed the rift between the Dominion and our universe. Like running a needle and thread through the vortex, st.i.tching it together again.'

Kerstin and Fitz approached, supporting each other.

The Doctor looked at each of them in turn. 'It's going to be a close-run thing. All the energy in the wormhole is heading back here there'll he a nasty implosion. I managed to buy us a few minutes, but that's all.'

The feedback you said it would destroy Earth,' said Fitz.

The Doctor nodded, talking fast. 'Imagine a huge elastic band, stretched out to its fullest extent, one end of it attached to Earth, the other to the Dominion.'

Fitz grimaced. 'I get the idea.'

The Doctor continued. 'It could destroy Earth but I'm going to try to adjust the parameters with the TARDIS's dimensional stabiliser so it will only affect this base and the area around it.'

'What'll happen to the TARDIS?' said Sam.

The Doctor looked grim. 'She'll withstand the impact. I hope.'

Oh great, thought Sam. 'What about the T'hiili?'

The Doctor winced, as if he'd been hit. 'They... might might survive.' survive.'

Fitz swore.

A hard lump was forcing its way from Sam's stomach to her throat. 'What about us?'

The Doctor blinked, and looked away into the distance. 'I want you to get out of here. Get out of the C19 base, into the forest, and run. There should be enough time for you to outrun the implosion.' He operated the door lever.

'We can take the T'hiili with us!' said Fitz imploringly.

The Doctor shook his head sadly. 'They'll die in Earth's gravity, remember? They'll have to take their chances with the TARDIS and me.' He grimaced. 'I didn't plan it this way at all.'

Sam had never seen him so distraught. She could hardly believe it herself. After escaping the Blight, the T'hiili were facing destruction again.

'What about you?'