'What?'

Nagle switched off the monitor. 'It was a savage, uncontrollable carnivore. Fortunately, it couldn't get out of the generator chamber. After a while it died, apparently from natural causes. It's down in the lab; you can have a look at it later.'

'No need,' said the Doctor. 'I've had a close encounter with those things. Which leads me to ask, how did those things get to the farm? I have a nasty theory which I hope you're going to refute.'

'Well, after that creature came through, we had to close down. So I shut off the power to the generator and closed the nodes.' Nagle took off her gla.s.ses, and began to clean them again. 'But that wasn't the end of it. The abductions happened after that. And the attack on the farm.' Her face creased into a frown. 'I just don't understand it.'

'Unfortunately, I do,' said the Doctor. 'It's as I feared. Your little telecongruency warp has created a wormhole between the two nodes, operating independently of the generator.'

Nagle almost dropped her gla.s.ses. Recovering, she managed to slip them on, her eyes wide in disbelief. 'A wormhole wormhole? As in Einstein-Rosen bridge?'

'Yes, if you like,' said the Doctor, looking over at the generator. 'A tunnel connecting two places in s.p.a.ce-time.'

'I know what a wormhole is, Doctor. But naturally occurring wormholes are supposed to be tiny, existing only at the quantum level, for very brief periods of time.'

'Some races use them to navigate their way around the universe,' said the Doctor. 'Some even use them for time travel, because to a wormhole s.p.a.ce and time are the same.'

'But... but how can it exist? What's holding it open?' She gave a little snort of disbelief. 'Cosmic string?'

'No,' said the Doctor. 'I don't know. Some sort of energy? Must be something to do with what's at the other end.' He tapped at the keyboard.

Nagle looked anxious. 'What are you doing?'

'Calculating the size of the wormhole.' Figures danced across the screen, and as he read them the Doctor's hearts sank. 'Well, I congratulate you, Professor.'

'I must admit,' said Nagle, her voice hushed with pride, 'creating a wormhole, even by accident, is a ma.s.sive advance '

The Doctor cut her short. 'Advance, my pants! By fiddling about with alien technology, you've raised a dragon you cannot feed!'

Nagle frowned. 'What?'

'Professor Nagle, you have inadvertently created a dimensional anomaly which could destroy the Earth.'

Fitz walked along the corridor, trying to hide his fear, Kerstin beside him, presumably doing the same. He didn't know he couldn't see her face behind the faceplate. The suits were light and surprisingly cool, but the helmet was confining, though the triangular faceplate allowed a fairly wide field of vision. There was a strange chemical smell which was beginning to get on his nerves, and his breathing sounded loud in the confines of the helmet.

They'd walked along the curving brick-walled corridor for quite a time, without meeting a soul. On the inner wall at intervals were green doors with numbers stencilled upon them. All were locked, except one or two, which were empty. From the look of it, Fitz reckoned that this corridor was little used. The brick was old and crumbling, spider webs thick with dust stringing down from the ceiling. Not all of the bulbs were working, which made it very dark and creepy.

'This is fun, isn't it?' he said to Kerstin.

'No,' said Kerstin uncomprehendingly, her voice m.u.f.fled by her helmet.

Fitz bit his tongue. What a stupid thing to say! b.u.g.g.e.r it, he was taking her for Sam again. Kerstin was still obviously too stunned by Johan's death to want to respond to humour. Fitz recalled the time after his mother's death. For a while, humour had seemed meaningless, and people, with their quirks and mannerisms that he could usually feel so superior to, were just annoying a noise to be shut out.

That must be how Kerstin was feeling now. A wonder she was here, walking with him into the heart of danger, rather than going away somewhere quiet to grieve as he had done. Perhaps she was so numb that she no longer cared what happened to her.

They walked on in silence.

The corridor ended abruptly in a white-painted bulkhead, two steel double doors set into the wall. Lift doors. There was an arrow illuminated in a metal panel between the doors, indicating only the up direction.

Fitz reached out to press the b.u.t.ton, and hesitated. 'Kerstin,' he said, 'take off your helmet a minute.'

She did do, taking deep breaths her suit must have the same chemical tang as his. 'What is it?' she said, pouting slightly.

'I don't know what I'm getting us into,' said Fitz. 'The people behind this place obviously have something to do with what happened to Johan, so if you want to go back to the forest and wait '

She cut him off in mid-sentence. 'No. I'm coming with you. I want to find out what's going on.'

'Are you sure? Even though we might get shot or or worse?' Was he he sure? What the h.e.l.l was he even doing here? sure? What the h.e.l.l was he even doing here?

Her blue eyes glittered. 'Yes!' She reached out and pressed the lift b.u.t.ton. The doors on the left opened almost instantly and they stepped inside.

The interior of the lift was carpeted and mirrored, but one of the mirrored panels was cracked and the carpet was faded, scuffed and torn. Fitz was faced with a row of b.u.t.tons. The B b.u.t.ton, the lowermost one, was lit, and above that were four other floors.

'Which one, which one?' muttered Fitz.

Kerstin reached out and pressed 2. She managed a brief smile. 'My lucky number.'

The lift seemed to travel for quite a distance, back up towards the forest. Fitz imagined the dark ma.s.s of trees and vegetation, silent and brooding, the perfect cover.

Suddenly the lift stopped with an efficient 'ping' and the doors slid open, to reveal another corridor, this one brightly lit, with white-painted walls. It curved in two directions away from them.

'Left or right?' said Fitz, letting Kerstin choose. Why not? Her guess was as good as his. And it was probably important for her that she felt she was in control.

'Left,' said Kerstin.

They stepped out and moved along the corridor. 'Put your helmet back on,' whispered Fitz, motioning to Kerstin as he slid his back on.

They'd walked only a few yards along the corridor when a short man in a white lab coat hurried round the corner. He caught sight of Fitz and Kerstin.

'What are you doing here?'

Fitz's mouth went dry and he felt Kerstin tense beside him.

It was Dr Lindgard.

Professor Nagle watched as the Doctor sat at the computer, occasionally tapping at the keyboard, raising his eyebrows as data scrolled down the screen. She was still reeling from what he had told her.

'This is no normal wormhole,' he said. 'It's a veritable Ouroboros. It has random-shooting branches which fork out from the main ma.s.s. One of those must have invaded the TARDIS.' He glared up at her. 'Are you beginning to realise the enormity of your folly?'

She was still finding it hard to believe. Creating a wormhole wormhole? It was way beyond anything she'd planned. 'Yes,' she lied. 'I am. That's why I need your help.'

The Doctor shook his head. 'You know, I should really be intolerably angry with you, and your blind scientific fumbling. But I may as well be angry with the whole human race. Its curiosity is commendable but it never actually learns what to do with the things it discovers. And alien technology in the hands of humans a lethal combination.'

Enough with the lectures, thought Nagle. 'But will you help me?' she said, trying to keep her voice calm.

The Doctor's face darkened. 'I have no choice. If I don't help, if I leave things as they are, then the wormhole could grow to tremendous size, and consume the Earth. And on a personal note ' he glanced over at the generator 'Sam's at the other end, alive, I very much hope.'

Nagle shrugged, feeling a glow of satisfaction flood through her. For whatever reason, the Doctor was going to help. 'What's your diagnosis, Doctor?'

'Well it's pretty obvious to me what's happened,' said the Doctor. 'The telecongruency beam got caught up in something, probably a black hole. The laws of physics go a bit doolally when singularities are involved. There must have been some energy trade-off, and a wormhole was formed between the two nodes of the telecongruency beam.'

None of this made any sense to Nagle. She half suspected he was making it up. 'So, how can we shut down the wormhole?'

The Doctor's face clouded. 'Somebody has to go through it. Find out what's at the other end.'

This was madness. 'It's too dangerous, Doctor. What happened to the probes '

The Doctor waved his hands in the air, suddenly angry. 'Oh, socks to the probes! This whole thing has gone too far and it ends now. I'm going through.'

Nagle bit her lip. If they activated the node, who knew what would come through. 'You know it might be a one-way trip.'

The Doctor set his mouth in a grim line. 'I have no choice.' He stuck a finger in his mouth and frowned. 'Now, which b.u.t.ton switches this thing on?'

As Nagle opened her mouth to speak she noticed all the soldiers in the control room suddenly crash to attention. She groaned. 'Oh, h.e.l.l.'

She turned to look towards the entrance to the control room, her heart turning to lead. Major Wolstencroft, in full uniform, was walking down the entrance ramp, Captain Rogers at his side.

Major Gareth Wolstencroft was a tall, broad-shouldered man, with the handsome, chiselled face of the cla.s.sic military leader. His bald head, which he shaved daily, gave his face a pugnacious look. His eyes were small and dark, his mouth wide and unsmiling. He had an aura of power about him, a charisma of control. Everyone reacted to his presence, sitting up straighter, coughing nervously, fiddling with pens. Everyone except the Doctor, who was still bent over the generator control desk.

Nagle got up from her chair and approached Wolstencroft. 'Major. To what do I owe this pleasure?'

He shot a look at Nagle, which rooted her to the spot. It was absolute controlled fury.

Nagle gritted her teeth. Whatever he was going to say or do, she was still in control of this operation. She was a senior C19 scientist, he was just a UNIT soldier. A major, but still only a soldier. She forced herself to smile at him.

'Professor Nagle, don't try to ingratiate yourself with me,' he said in his clipped, cultured voice. 'There has been a serious breach of security.'

The creatures at the farm. 'We'll make up a cover story it's worked before.'

'People have died,' snapped Wolstencroft. 'It's too late. Nothing you say or do will change my mind about the status of this operation.'

Nagle swallowed. She knew what that meant. It was the end.

'I I ' she began, but Wolstencroft wasn't listening.

'Who is that man?' he said, pointing with a gloved finger over to where the Doctor was poring over the controls to the generator.

Captain Rogers coughed. 'That's the Doctor, sir.'

Wolstencroft's eyes widened and he raised his eyebrows, his smooth forehead wrinkling. 'Oh yes,' he said. 'The Doctor. What's he doing here?'

Nagle decided it was about time she regained some ground. 'He's working with me on the generator.'

Wolstencroft smiled, but there was no humour in the expression. 'Not for much longer.'

She couldn't blame him, she supposed. As head of security, he had a duty to protect people. But, G.o.ddammit, now the Doctor was here she was so close to a breakthrough.

She watched Wolstencroft approach the Doctor. 'You there! Stand away from that desk.'

The Doctor turned, his face dreamy and abstracted. 'Oh, h.e.l.lo,' he said upon seeing Wolstencroft. 'I was just '

'You were just about to stand away from the control desk,' said Wolstencroft in a voice of ice.

Out of the corner of her eye, Nagle saw the UNIT soldiers c.o.c.k their rifles. This was madness. The Doctor was on their side their side.

The Doctor stood away from the control desk. 'Umm, why are you all pointing guns at me?' he said plaintively. 'I'm the man who can save the day, you know!'

Wolstencroft's eyes narrowed. 'I know all about you, Doctor. Every time you turn up, chaos ensues. You're not going to save the day, because I am.' He stepped back from them, raising his voice to address everyone in the control centre. 'As of now, this operation is over. We are moving out in ' he glanced at his wrist.w.a.tch 'thirty minutes.'

Nagle stepped up to the major. 'You don't understand! You can't shut it down.'

Wolstencroft ordered Rogers to restrain her. 'I can and I am. We're moving out.'

'Doctor, tell him!' said Nagle.

The Doctor opened his mouth to speak but found himself in the grip of two burly UNIT soldiers. 'What?'

'Put him in the cell again. I don't want him getting in the way.'

The Doctor was dragged away. 'You fool,' he cried. 'She's right! You can't shut it down!'

But they weren't listening. They were obeying orders. Stupid, ill-thoughtout orders, but there was nothing the Doctor could do about that.

Nagle watched as the Doctor was dragged away.

'That was a stupid thing to do,' she hissed, hating Wolstencroft as much as she had ever done. 'He was going to help us!'

Wolstencroft bore down on her. 'The matter is closed, Professor. This operation is of no concern to you any more.'

He walked over to a comms desk at the side of the room.

Fitz willed Kerstin to be calm as Dr Lindgard looked them up and down. He opened his mouth to speak when a voice blared from a small speaker on the wall.

'This is Major Wolstencroft. There has been a major breach of security and this operation is compromised. Therefore, as of now, this operation is closed down until further notice. All C19 personnel are to evacuate and travel to Stockholm for a debriefing. A skeleton crew will remain in this base to monitor the equipment. All specimens are to be destroyed.'

Lindgard listened to the message, his mouth dropping open. When the message ended, he sighed and shrugged. 'Ah well, I was expecting something like this.' He pointed at Kerstin and Fitz. 'You two come with me. We might be able to salvage something.'

He turned and marched along the corridor. Fitz began to follow, but Kerstin just stood there.

'Come on,' said Fitz. 'We don't have much choice!'

They followed Lindgard past the lifts and along a wide white corridor lined with doors. These doors were steel, and they had hefty locking mechanisms and hydraulic hinges.