'Cal Tyko,' he introduced himself, 'duty nurse. I take it this is the prisoner?'

He glanced at the Doctor without really seeing him. When Waller corrected his misapprehension, repeating the Doctor's cover story, Tyko's features clouded. It was obvious he thought this a waste of his time.

'We won't get in your way,' the Doctor promised.'I'm just looking for a few scare stories you know, what happens to you when you lie, who comes for you, that kind of thing. Maybe a bit of technical jargon to make it sound plausible.'

Tyko raised an eyebrow. 'You need to make the truth sound "plausible"?'

'We've got compet.i.tion these days, in case you hadn't noticed.'

Tyko sighed. 'You mean Gryden, don't you?'

'Dead right. What I want from this doc.u.mentary is to restate a few basics but to back them up with evidence, make sure people believe us and not what they might see on the other side.' As he spoke, the Doctor darted around, making the shape of a TV screen with his fingers and looking at Tyko through them.

The nurse's att.i.tude softened. 'I can give you an hour. I'm into overtime already, but the morning shift is shortstaffed. And I've rounds to do you'll have to keep up.'

'Glad to,' said the Doctor enthusiastically. 'I want to see everything.'

Tyko took them to a lift and up to the first floor of the tower block. 'I wish someone could could do something about Gryden,' he lamented as he led them along a series of whitelit corridors. 'Every other patient we get in here these days has something to say about that fellow. And they're coming in thicker and faster. We don't have the beds. We've been sending the minor cases out to private clinics. I tell you, if I could get my hands on him...' do something about Gryden,' he lamented as he led them along a series of whitelit corridors. 'Every other patient we get in here these days has something to say about that fellow. And they're coming in thicker and faster. We don't have the beds. We've been sending the minor cases out to private clinics. I tell you, if I could get my hands on him...'

'Yeah,' said the Doctor mildly, 'but "if" is a dangerous word.'

Nurse Tyko nodded, looking a bit shamefaced. They came to a whitewashed metal door. Tyko opened a hatch in it to reveal a barred window. Through this the Doctor could see a tiny dorm with another barred window at its far side. It was furnished with a bed, a chest of drawers and the ubiquitous flat TV screen taking up fully half of one wall. The TV was on, but the sound was turned down, the subt.i.tles on. A young woman lay on the bed, wearing a plain white nightgown. She was painfully thin.

'Morning, Su,' said Tyko. 'You had your breakfast?'

'I've been a good girl, Mr Tyko. I ate it all up, I did.'

'You know we can check, don't you? Show me the plate.'

The woman gave him a resentful look, then forced herself into a sitting position, picked up an empty plate from the floor and tilted it towards him.

'Very good, Su. The orderlies will collect it soon. Do you need a pill this morning?'

Su shook her head. Tyko nodded, satisfied, and closed the hatch.

'I think we're getting somewhere with Su,' he said as they strolled on. 'Of course, the orderlies will check under the bed and behind the drawers, but it's been a few weeks since she lied to us, and she's certainly getting stronger. Silly girl, she wanted to look like the women she saw on Static. Her friends told her that imaginary food tasted as good as the real thing and helped you lose weight. When she first came in, she could hardly stand by herself.'

'She can't tell fantasy from reality, is that it?'

'Who can?' said Tyko. 'This next fellow, he couldn't accept that his grandma had pa.s.sed away. He kept her in his flat for six months. He imagined she was talking to him. It was only when she persuaded him to take her out shopping...'

'Ah,' said the Doctor.

There were more after that many more, filling dozens of rooms and no doubt many more above them. People who had been committed for fraud or a.s.sault or just for eccentricity, all with one thing in common. They had acted as they had, or so they claimed, because they had believed in something unreal: voices in their heads, whispers behind their backs or just dreams of bettering themselves.

Tyko addressed each of them with unstinting politeness, dispensing encouragement and guided by a data pad pills in varying strengths and dosages. Sometimes he made a note on the pad before they moved on. The Doctor strode alongside him, ever cheerful, hands clasped behind his back, asking interested questions. Waller said nothing, a brooding presence in her black police helmet. Only when Tyko commented that the number of admissions for violent crimes had increased sharply in recent months did she grumble something to herself.

Back on the ground floor, the Doctor spotted signs for two operating theatres. Tyko was adamant that they were offlimits. A sterile environment, he said and any further discussion was forestalled by the bleeping of his pager.

The nurse unclipped the small white device from his belt, read a message on its screen and scowled. 'It appears I won't be home on time today after all,' he said. 'They've just brought us another guest.'

Arno Finch didn't resist as he was unloaded from the back of a police transport vehicle. It was only when he saw where he was that he began to struggle. He was outnumbered, though, and his hands were still cuffed.

Four cops carried him into the Big White House, four more following with guns drawn. Nurse Tyko made a token attempt to direct them, but they knew where they were going.

'Strictly speaking, there should be a doctor handling this,' Tyko confided to the Doctor and Waller as they hurried after the new arrivals, 'but we're stretched to the limit.'

'And you can't take on more staff?' the Doctor ventured.

'No,' said Tyko and Waller in unison.

'Cos that's not the way things are. OK.'

He recognised some of the officers from the scene of Finch's crime. They'd raced past him into the office block as he and Waller had left it. Waller hadn't even acknowledged them, marching stiffly up to her bike, keen to move on. Of course, the Doctor never liked to stick around for the mopping up either.

Tyko showed them into a small, windowless room with a desk, two chairs and a computer, and shut them in. Two walls were covered in TV screens. Each showed the inside of an inmate's room the cameras seemed to be hidden behind their own TVs apart from the biggest, most central screen, on which a featureless cell with white padded walls was displayed. A moment pa.s.sed, then the door of this cell flew open.

Arno Finch was hurled to the floor, unable to use his hands to break his fall. Four cops took a limb each and pinned him down as Tyko came in, holding a hypodermic needle filled with a clear liquid. The nurse stooped beside Finch, muttered something soothing to him, and slid the needle into his neck.

'What's he doing?' asked the Doctor.

'Shutting down the right hemisphere of the brain,' said Waller stiffly. 'That's the subconscious side, the side that deals with fiction.'

'Yeah, I know what it does.'

Tyko straightened and nodded to the escorting officers before leaving the room. One of the cops directed two bursts of a solvent spray at Finch's bound wrists, then hurried out with his colleagues. The door closed again and the Doctor could hear the clunks of locks being engaged.

'They got here quick, don't you think?' he remarked to Waller.

'Maybe there was a wagon in the area.'

'Not what I meant. Your lot must have brought Finch straight here. No questioning, no trial, nothing.'

'No need,' said Waller. 'He's a fiction geek. It's up to the doctors to decide his treatment. You'll see.'

Cal Tyko had appeared in the white cell again, without the door opening. A hologram, the Doctor deduced, probably operated from a nearby control booth. It gave off a telltale fizz as it stood beside Finch, who was lying where he'd fallen, blubbering to himself. Tyko spoke to him in gentle tones, a.s.suring him that he was safe, that the doctors would protect him from the nightmares and that if he could just answer a few simple questions and provide his credit number then everyone would be happy.

Finch, his hands free now, tried to lever himself into a sitting position. He gave up and burst into a renewed flood of tears when he realised that the left side of his body was paralysed.

'It's OK,' Tyko rea.s.sured him. 'This is just a temporary side effect of your medicine, that's all.'

The Doctor glanced at Waller. 'You must be hot in that helmet.'

'I'm fine.'

'Must be stuffy,' he said. When she didn't answer, he persisted, 'just wondered what it's for, that's all. You don't reckon you need protecting in here? Didn't think so. And it can't be to intimidate the bad guys, cos that'd imply you want them to use their right hemispheres. You know, to imagine what's behind the black visor.'

'They don't have to imagine,' said Waller sharply. 'They can see I'm a police officer. That's all anyone needs to know.'

On the screen, the holographic Tyko was asking Finch about his childhood. The answers came resentfully and were slurred as Finch struggled to speak through one side of his mouth. Tyko responded to each one with a weary tick on his data pad.

'OK,' said the Doctor. 'My fault. I know you didn't want to come here. I thought maybe you had something to hide.'

There was a long silence. The Doctor stood, smiling innocently.

He didn't expect Waller to lie, of course. Which left her with only one choice.

She took off the helmet.

They both stared fixedly at the screen for a few seconds. Then the Doctor risked a sidelong glance. Waller was a darkskinned woman, approaching middle age, with shaved greying hair and a misshapen nose that had obviously been broken a time or two. She was standing almost to attention, obstinately avoiding the Doctor's eye.

'Nope,' he said. 'Don't see anything wrong there. Two eyes, two ears, the right number of noses, all in the right places. No hideous scarring. Must be the other thing, then.' Waller didn't take the bait, so the Doctor asked a question of his own. 'When were you here?'

'A lifetime ago,' she confessed grudgingly.

'But you're still afraid they'll recognise you. Was Tyko here then?'

'No. It can happen to anyone, you know.'

'I'll bet.'

'I was a teenager. You know what it's like. No matter what they tell you, you can never quite resist the dreams. The dreams feel good. Until you get older. Until it goes bad for the first time.'

'How long did they keep you in?'

'Sixteen months,' said Waller bitterly. 'Sixteen months out of my life, and the worst thing is I've no one to blame but myself. No one can say they weren't warned. No one can say they haven't seen.'

'But they let you go.'

'I was one of the lucky ones. They taught me to repress the images. I couldn't do my job otherwise. It means everything to me, Doctor. When I'm out on the streets, on my bike, everything is clear. Everything is black and white. I know the procedures. I can throw myself into the work because it's real, because it's now, because I enjoy it and because, while I'm doing it, it's as if the ghosts aren't there for a while.'

Tyko had finished his questioning of Finch. He explained to him that he'd be kept in the padded cell a while longer, under observation, to make sure he wasn't a danger to himself. Then, as soon as a room became free, he would be moved to it. Finch nodded, accepting his fate without argument. He dragged himself into a corner, hampered by a useless arm and leg, and moped there.

'You ever see Static?' asked the Doctor.

'No,' said Waller. 'Doctor... this doc.u.mentary of yours. I can't be a part of it. It's best that way. After we leave here, I can't see you again.'

It was a long time before either of them said another word.

'Y'see,' said the Doctor, 'I get that fiction is dangerous. Took me a while, but I get it now. I even understand how, but not why.'

Tyko slid a plastic card through a reader beside the main entrance door clocking off, the Doctor surmised and led his visitors out into the grounds. 'We don't ask that question,' he said.

'You don't ask much at all.'

'We don't like to imagine the answers.'

'But you know this isn't right. You haven't forgotten your history. You know the human race dreamed once, or you'd never have got this far.'

'True,' said Waller, 'but look what it cost them. Our ancestors flirted with madness. They let their criminals run rampant, accepted that their leaders would always lie to them, fought wars over things they couldn't see. Billions of them suffered and died to give us what we have now.'

'And what is that, exactly?'

'A stable and workable society. A reality in which we can all live, in which we don't have have to dream any more.' to dream any more.'

'No, I'm not having that.' The Doctor shook his head stubbornly. 'I'd say it was hysteria, but I don't see any other symptoms... Kids aren't affected, you said?'

'There have been no extreme cases under the age of thirteen,' said Tyko.

'Though it's best they learn to resist fiction from the start,' said Waller, 'get them into the habit.'

'You're living in fear,' opined the Doctor. 'You're living in fear, and you're too... too mired in dogma to do anything about it.'

Tyko shrugged. 'It's the way things are. We've good reason to be afraid of the big bad wolf.'

'Oops,' said the Doctor, 'now you're using a metaphor.'

Tyko shot him a glare, but then forced a smile. 'You're right again, of course. Now, if you'll excuse me, both of you, I have another shift in a few hours.'

They had reached his car though how Tyko could tell it from all the other grey vehicles was a mystery. He climbed into the driver's seat and started the engine.

'I have to go too,' said Waller, stifling a yawn. She put her helmet back on and made for her bike. 'Can I drop you somewhere?'

The Doctor had stayed out longer than he'd meant to. Rose and Captain Jack would have woken by now and found him gone.

'I'm staying at a hotel,' he said, 'just round the corner from where we met.'

Waller grimaced apologetically. 'It's a bit out of my way.'

'I'll blag a lift off someone. It's no trouble.' He just hoped his companions hadn't done anything unwise. They didn't know what he now knew.

Waller nodded and kicked her bike into gear. As it rose on its jets, she said she hoped the Doctor's research had been fruitful. He a.s.sured her that it had. She hesitated.

'Our world,' she said. 'Its name. I did hear something. It was a long time ago. Some of the girls at school, they said it was called I mean, it used to be called Journey's End. As if this was where we came to put our struggles behind us.'

The Doctor flashed her a grateful smile.

Waller rode to the gate, her bike's engines whining, and he followed on foot, waving to the guard as he pa.s.sed him.

The street outside the Big White House was almost empty. As if everyone drivers and pedestrians alike avoided this block when they could.

Standing alone, the Doctor let his facade slip for a moment. He watched Waller's bike receding into the distance, until it turned onto a road clogged with traffic and was gone. He remembered all she had said to him and he felt a stab of remorse. He empathised with her a great deal more than she could ever realise.

But he also knew what he had to do and he knew that, like it or not, Inspector Waller would be one of the first casualties.