And in the middle of them, outside the door, Sergeyev staring sightlessly at the night sky. His gun by his side and his face crumpled and pale like an old paper bag.

Jack gritted his teeth. Reached up with his free hand to pat Valeria's unfeeling head. 'We'll be OK. I promise.'

Then Jack was running for their lives.

Klebanov had suggested the Clean Room. The Doctor wanted somewhere isolated and quiet where Georgi could concentrate, away from distractions. The Clean Room was a gla.s.s cage in the corner of a large, bare room. Just a wooden desk and an office chair remained. There was a complicated electronic locking system on the double set of doors that acted as an airlock, operated from a numeric keypad. The gla.s.s was bullet* and blast*proof. The cage was empty apart from several gas canisters piled up at the back of the room. They were stamped with a red skull and crossbones.

'It is where we used to work on contagious bacteria,' Klebanov told the Doctor, Rose and Georgi.

'We still have some, as you can see.' Minin pointed to the canisters. 'This seemed the best place to keep the stuff. With the doors closed it's completely sealed.'

'Can't you destroy it?' Rose asked. 'Or, I dunno, send it back?'

'No one wants it back,' Klebanov told her.

'Decommission it? Make it safe?' the Doctor suggested.

'The equipment for that went long ago,' Alex Minin explained. 'Traded for other supplies. More urgent things like food and oil.'

Klebanov grunted, but did not disagree. 'Will it do?'

The Doctor grinned. 'It's great. Let's find Georgi here a chair. Then I'll have a little talk to him. After that we have a few other things to do while he gets on with it.'

'Like what?' Rose wanted to know.

'Like checking on our bonfire. Like burning a few blobs.'

Minin opened the door by tapping a code into the keypad. He carried the chair from the desk through into the area between the two doors, closing the outer door behind him. Then he tapped the code into the keypad within the airlock and the inner door clicked open. He put down the chair.

'Let's get started.' The Doctor led Georgi to the door. 'What's the code?'

'1917,' Klebanov told him.

'What else?' The Doctor tapped it in and led Georgi through.

Once he was seated in the chair, the Doctor spoke quietly to him. He put his fingers to the old man's temples, relaxing him, putting him into a trance. Minin watched with interest.

After a while, the Doctor stepped away. He put his finger to his lips as Minin made to speak and nodded at the door. The two of them left the cage, Georgi sitting inside, alone, staring at the gla.s.s wall in front of him.

'Someone should stay with him,' the Doctor said.

'I'll do it,' Rose replied at once.

'No, I need you with me. Minin can I trust you?'

'I hope so, Doctor.'

'I hope so too.'

'What do I need to do?'

'Probably nothing. Just make sure he's all right. There a phone in here?'

Klebanov went to the bare desk on the other side of the room. In a drawer he found a phone and plugged it into a wall socket. He lifted the receiver to check it was connected. 'Extension 514.'

'I'll need the full number,' the Doctor said. 'Any problems, I'll call you on Rose's mobile. You can give Georgi new instructions to pa.s.s on to the blob things. He's in a receptive state. You won't know it, but he'll hear you.'

'Will it get a signal? None of the radios are working,' Klebanov pointed out.

'Super phone,' Rose told him. 'It'll work.'

Klebanov gave the Doctor the number. Minin sat on the desk, watching Georgi. 'Will he just sit there, like that?'

'I hope so. Come on, Rose work to do.'

Klebanov followed the Doctor and Rose to the door. Then he paused and turned back to Minin. 'It could he a long night,' he said. 'Get yourself a coffee. I'll wait here with Georgi till you get back.'

'So what's going to happen?' Rose asked.

They crossed the paved compound outside the inst.i.tute and started down the road.

'Georgi has managed to get on the same wavelength as the ship's psychic communication with the remotes.'

'Like when he saw what they were up to before?'

'Right. Only this time he's talking to them. I hope he's filtering out the ship's messages and adding his own instructions.'

'So, he's, like, hacked in?'

'Yeah. He's hacked in. And he's telling them all to come here.'

'To get us?'

'Well, not really. That's what they think so far as they think at all. But they just do what he tells them now. And he's telling them to come along this road and keep going. Into that.'

The Doctor pointed to the ma.s.sive pile ahead of them blocking the road and stretching across the narrow ridge.

'And that'll stop them?'

'Will when it's on fire. They like the cold. Any energy they draw doesn't come through as heat because it's pa.s.sed straight on. The shock of a sudden temperature change as they go into the fire ought to deactivate 'em all. Can't really kill 'em cos they're not really alive, you see.'

'Ought to,' Rose echoed.

'Yeah.'

'Bonfire night and a half, then.'

'Yeah.'

'So when do we light the blue touch*paper?'

'Soon as we see them coming.'

They had reached Levin and his men, standing looking at their work. The colonel turned to the Doctor, hearing his last comment. 'They're coming now,' he said. 'Look.' He pointed past the side of the pyre, into the valley below. A line of glowing blue was vaguely visible through the drifting mist.

'Charges are set,' Lieutenant Krylek reported. 'We can light her up as soon as you're ready.'

The Doctor was looking down into the valley, watching the blue glow edge slowly closer, wondering where Jack had got to.

'Let's do it,' he said.

Uphill was bad news. Jack had to put the girl down. She could stand. She could walk. She just didn't seem to know she was doing it. Just stared straight ahead into the misty darkness and let Jack lead her.

Running seemed like too much to ask. She was a sleepwalker no sign of consciousness, just one foot in front of the other. Her old face framed by young hair was devoid of expression. Her eyes showed no flicker of recognition as Jack urged her onwards. He held her by the hand, pulling her along as fast as he could.

If he went too fast, she stumbled and fell. She made no effort to save herself, and her clothes were soaked from the snow, her face scratched, her hair dishevelled. Least of her problems, Jack decided.

He was out of breath, nearly exhausted. 'Not far now,' he gasped, though he knew he was only saying it for his own benefit. 'Just up the hill. Almost there.'

But behind them he could see a line of the creatures starting up the road in pursuit. Were they really following? Did they know Jack and the girl were there could they sense them? Or were they just making for the inst.i.tute at the other end of the road?

Jack and Valeria were struggling along a narrowing ridge. At the sides of the road, the land dropped away into deeper darkness. Jack could only tell because the pale glint of the snow just stopped where the ridge ended. 'Come on,' he encouraged Valeria could she hear him? Probably not. But he said it anyway: 'Come on. Not far. Almost there. We'll be all right in a few minutes.'

Behind them the creatures were edging closer, catching up.

Ahead of them the night exploded.

Fire leaping high and wide as the entire ridge burst into flames. The heat of it almost knocked Jack backwards. The whole ridge was burning, the snow retreating from the heat as it melted and evaporated from the roadway. There was no way they could get through to the inst.i.tute now.

But perhaps the heat would drive the creatures back. 'They don't like fire and heat,' Jack rea.s.sured Valeria. Her expression did not change. He squeezed her unfeeling hand. 'We'll be fine now. They'll turn back. You'll see. Any moment now.'

But the creatures kept coming.

TWELVE.

The Doctor was counting on his fingers, peering through the smoke and flames. It made Rose's eyes sting and she blinked and squinted.

'Thought there'd be more of them,' the Doctor was saying.

She couldn't look. The smoke was everywhere, thick and black from the fuel oil. Rose had to turn away. And as she did so, as she blinked and coughed and the tears ran down her cheeks, she could see the inst.i.tute framed against the night sky behind them. The firelight was a flickering orange across its blank concrete facade. But it was an orange tinged with blue.

From either side, across the snow*clad fields and from the cliff top, far in the distance the creatures were coming. She pulled at the Doctor's sleeve. 'Look.'

'It's great, isn't it?' He was still staring into the flames. 'We've got 'em licked.'

'We haven't got 'em licked. Look.' She pulled harder.

'They've come round the sides,' he said quietly.

'We could set up more fires,' Lieutenant Krylek suggested.

'Doubt there's enough time,' the Doctor told him.

Levin was nodding in agreement. 'And we've nothing left to burn.'

'So what's gone wrong?'

The Doctor took a deep breath 'Georgi,' he said. 'Either he's not succeeded. Or...'

'Or what?' Levin demanded.

'Barinska wasn't working alone.' He clicked his fingers. 'Phone.'

Rose handed him her mobile and he punched the b.u.t.tons. He was already running, back towards the inst.i.tute. 'Keep the fire burning,' he shouted at Levin. 'Maybe we can still lead them here.'

They were huddled as close to the flames as Jack could stand. Valeria didn't object, didn't seem to feel the heat or appreciate the danger. And still the creatures edged closer. Jack reckoned they had maybe ten minutes. At most. Then he would have to drag Valeria to her feet, maybe carry her, run for it hope to get through the ma.s.s of glowing blue flesh that was rolling up the roadway towards them.

'Fat chance,' he murmured.

He held her tight, arm round her shoulder. There was no give at all, no recognition or reaction. It was like holding a corpse.

The sound of the phone in the quiet of the room startled Minin. It took him a moment to recover, then he s.n.a.t.c.hed at the receiver in sudden excitement.

'Doctor? Has it worked? Have we done it?'

But he could tell at once from the Doctor's tone that things were not going well. 'What's Georgi doing? Can't he concentrate? Has he woken from the trance?'

Minin looked into the gla.s.s cage. 'No. He's just sitting there. Looks like he might be muttering something. But he's not moved. Not at all.'

'Then he's still in contact. Alex you have to break the contact. He's bringing the creatures round the side. He's bypa.s.sed the fire. He's leading them right to us.'

Minin felt cold. 'Stop him? How?'