Like a puppet, the boy looks around. How he can see, none can tell, as there are no pupils in his eyes. The mouth continues to move slowly, almost in a parody of speech. The red of his mouth is like an obscene flashing light. Blood streams from the pustules on his face. 'Release me,' comes a voice like gravel from his throat. 'Or I will kill you all.'

Romana has one horrible thought, one nightmare realisation. The Doctor is wrong. Valdemar is real. Valdemar lives!

She is disturbed to find that the boy seems to be staring at her. 'Doctor,' she says, slowly. The cold wind is back, sending goose b.u.mps rising up her bare arms.

Huvan stands and smiles. The grimace is a death mask.

The boy does not stop at standing. He starts to rise from the ground.

'There is no Valdemar,' the Doctor states. 'Don't believe it.'

'Come with me,' says the dark, supremely resonant voice.

Huvan forms the syllables of her name. 'Romana...'

She looks around, unsure of her next action. The Doctor steps in front of her. 'I'm sorry,' he says, 'she's all booked up.

Come down from there.'

Huvan raises an arm, as if to strike. Romana flinches; what does he want from her?

'No!' yells Stanislaus all of a sudden, and leaps heroically on to the stone table. 'Leave her alone!'

There is a deep throaty chuckle, a small movement from the floating boy and Tenniel Stanislaus explodes. Literally explodes.

As the pieces fall, Romana sees Huvan's pupils return and, with an expression of terrible suffering, the boy seems to deflate and collapse noisily to the floor.

Heat returns to the hall.

Romana looks at the Doctor, who seems stunned, too stunned to move. Pieces of Stanislaus sizzle everywhere.

A rustle from the drapes by the stone stairwell. Miranda Pelham pulls aside the curtain. 'Is it over?' she asks, like a frightened mouse.

Outside the palace, in the never-ending acid storms, Ashkellia is shrieking. Night falls as the planet spins. The clouds bubble and froth and the surface far below quakes.

The palace stabilisers jet and smoke with the effort of retaining stability.

Something is moving under the planet's surface, a charging rumbling monster of unbelievable proportions. It is as if some gigantic force is fighting for its freedom, tearing at the bonds that hold it down.

Kampp, awake at last after his phantom sleep, is conducting an autopsy on the dead guard. His hands shake as the palace rocks. Just what can be occurring up there?

Neville has ignored his messages, informing him of the Doctor's escape and the murder of one of his men.

Honestly, the Magus is impossible at times. All that spiritual nonsense, why do people bother? Kampp has always had other preoccupations, flesh being prominent amongst them. Flesh and blood and mortality the true canvas of the artist. So why do his hands shake so?

Apparently there has been some sort of disturbance with the children of the rich. That young, ugly protege Huvan. He has disappeared and so has Neville.

He is not worried about the genetically altered boy. Kampp has always had a deep distaste for ugliness; to work on Huvan would be a duty, not a pleasure. However, when Neville is lost too, it is time to worry.

It is undoubtedly the work of the strangers. Once again the guards are out searching for them.

As far as the butler is concerned, Neville should have let him loose on them as soon as they arrived. Pelham too, she always had a smart mouth. He would like to have worked on her long ago, held up that flapping tongue for her to see.

Kampp cannot stop his hands shaking. His sleek moustache itches. He stares down at the corpse in front of him, the sculptor's block of stone ready for the shaping. He feels odd, like time is standing still. He cannot account for his sleep, was not even aware that he had fallen asleep. He remembers the order to kill the Doctor, preparing the instruments and receptacles, walking to the cell. And then he was on the floor outside, with something like a sticky black stain on his head. The guards running towards him, panicked, one of their own struck down.

Kampp attempts to cut into the flesh. Something distracts his attention, something at the edge of his vision. He tries again. His hand trembles, he cannot hold the cutter still.

For some reason, he cannot take his sleek eyes off the guard's face. That expression... what did he see? What did he see? He feels a certain envy that something could have engendered such fear. It was a professional job, whatever it was.

This autopsy is personal; Kampp needs to know what killed the guard. He is never averse to learning new tricks.

At last, he gets his hand under control. He lowers the cutter to the guard's white chest. With his left hand he smooths the skin. It is warm beneath the glove. He draws a red line with the cutter.

Again, that thing, whatever it is, distracts him. Kampp blinks, as if a light is behind his eyes. What is wrong with him?

The guard's body should not be warm. Kampp spreads his hand, just to check. Impossible. And now it starts to glow, as if lit from inside. The contours of the body seem to warp and change, to expand into shapes he knows are impossible.

Something is crawling into his own eyes. The light burns, burns right into the pain centres of his brain. Something in his head strains for release, a white-hot scorching needle. It pumps through his eyes. Screeching, Kampp drops the cutter. Blinded, he reaches for his eye sockets.

'Oh, you beauty,' he purrs, impressed, as his mind is flooded.

The Doctor is racing to the library of the Old Ones, with Miranda Pelham in tow.

'That was unpleasant,' she huffs and puffs after him.

'It's going to get a lot more unpleasant if we don't do something about it,' he barks back, skidding into the vast repository.

'What exactly are we looking for?' Pelham asks, as she looks up at the thousands of bra.s.s cylinders on the wall.

'And how the h.e.l.l are we going to find it?' She leans against the long table, trying to get her breath back.

The Doctor rubs his chin. 'It's a question of knowing the referencing system. Once you know what you're looking for, the library itself should find it for you.'

'Simple as that?'

'Simple as that,' he affirms.

Pelham is finding the palace a cold and unwholesome place. For the first time, she is realising just how alien and ancient it all is. 'What about Huvan? That was a dirty trick of yours, making Romana look after him. G.o.d knows what he'll do to her.'

The Doctor is marching along the rows of cylinders, looking for something she can only guess at. 'He's developed some kind of emotional attachment to her...'

Pelham gives him a wry smile. 'Emotional. Yeah, right. Not the adjective I would have employed.'

'She is our only chance of containing him.'

'You mean Valdemar.'

The Doctor stops and faces her. 'There is no Valdemar. The sooner you realise that, the bigger your chances of staying alive.'

'But he spoke. We saw him!'

'No, we saw Huvan flexing his psychic muscles. He has presumably been indoctrinated into believing in Valdemar.

He has absolute faith that this is a fact. I'm sure Neville saw to that when he brought him up. Now his psychic powers have been awakened, the strain on his mind is too much for him to comprehend. His subconscious has converted this new power into something he can understand. To keep his sanity.'

'Ahh...'

'You understand now?'

'No. Not really.'

'Never mind. I think I do.' The Doctor has found a tiny socket, no more than a screw hole, in the wall. He points at it and stares wide-eyed at Pelham. 'Do you know what this is?'

he asks.

'Why don't you tell me?' Pelham is saturated with information. She doesn't think she can take in any more.

'It's a library ticket. A fail-safe in case of problems with the telepathic circuits.'

'Really? How does it work?'

The Doctor shrugs. 'I suppose I could try sticking my finger in it.'

'Isn't that awfully dangerous?'

'Oh no, I'm always sticking things in places I shouldn't.' He jams in a digit. He smiles. 'Aaaahhhh!' he bellows.

Somewhere in the wall, something electronic fizzes. Pelham makes to haul him back but he waves her away, his face creased in agony.

'I think that's right, yes. Should see something now.'

The library comes to life. Pelham looks up to see previously hidden cogs and wheels and slats and slots churning and moving. The cylinders are filing themselves along discreet, oiled pipes. The noise is relentless and echoing. She claps her hands to her head.

The Doctor removes his finger from the socket. He licks the digit, as though it had been burned. 'That should do it,' he says smugly.

'Do what?'

'Help us to find the psychic inhibitor that we need to suppress the effects of the higher dimensions.'

'You know,' Pelham sighs. 'I wish I hadn't asked.'

Two cylinders pop out of pipes to settle next to them.

Pelham sees they are like vacuum flasks, with ornately decorated heads. Exactly what the library of Valdemar should look like, she thinks.

'Come on,' says the Doctor, picking up the cylinders.

She places a gentle, restraining arm on his shoulder, determined to stop him. 'Look, give me an idea, at least. If I just know what to look for, two of us will find it more quickly than one.'

He thinks about it. She really believes he would rather get on with it on his own. However, reason gets the better of him and he offers her a seat, dropping the cylinders on to the floor with a clang. 'Whoops,' he smiles sheepishly.

'Who is Valdemar?' she asks, directly, with the uncomfortable feeling that everything she has ever done with her life is about to be cruelly swept aside. 'Be gentle.'

The Doctor toys with the lid of one of the cylinders. He is having trouble getting it open. 'Valdemar is an experiment,'

he says. 'The product of fantastically complicated trans-dimensional physics. The Old Ones were phenomenally advanced and that was the end of them. Why can't I get this lid off? It's perfectly simple.'

'Perhaps you're doing the wrong thing. Perhaps it's not supposed to come off. If Valdemar isn't in the tomb, what is?'

'Nothing. The tomb is a gateway. You see, this planet, the whole of Ashkellia, is a gigantic particle accelerator. You know what a particle accelerator is?'

'No.'

'Designed to smash a hole into the fabric of reality.'

'I said no, I didn't understand.'

The Doctor is not listening. He places the cylinder on the table and glares at it. 'Good. To punch a hole into the higher dimensions, you need an awfully big fist. An unbelievably muscular fist, in fact. Even my lot never really got to grips with it.'

'Your... lot?'

'Too dangerous, you see. Three-dimensional life...' He sits up and looks at her, thinking something through, '... even four-and five-dimensional life, is unable to perceive the higher dimensions. We lack the necessary sensory apparatus. I mean, there are theories that suggest that these organs lie dormant in the brain but... ah!'

He snaps his fingers.

'What?' asks Pelham.

'Telepathy! Perhaps that explains telepathy and why only certain people are rumoured to have the gift. Perhaps the sensory organs in some individuals are better developed. I suppose it's possible that telepathy, in fact all psychic phenomena, are utilisation of the forces of the higher dimensions.'

'So what happens if we get exposed to these higher dimensions without these extra organ things?'

'You've seen it, in the tomb. The man who attacked us.'

Pelham remembers. She realises, guiltily, that she has not thought about Erik at all.

'In both a mental and physical way, exposure to the higher dimensions drives us mad.' He is concentrating fully on the cylinder in his hand.

'I can understand that. About being driven mad. So this particle accelerator thing kicked it all off. If it's all so dangerous, why did they do it?'

'Curiosity. Insatiable curiosity. There was nothing left for them to learn. They were an ambitious species and they didn't know when to stop. Millennia ago, the Old Ones must have punched a hole in reality. That hole grew and grew until it threatened to swamp the universe we inhabit. A shadow, spreading like a cancer, breaking down the barriers between dimensions. It consumed the Old Ones, it must have consumed nearly everything.'

At last, Pelham is beginning to see. 'Which explains the myth. So,Valdemar was just a hole in s.p.a.ce.'

'What? Just a hole! Not just s.p.a.ce either. Time, thought, imagination, everything. Every life form it encountered experienced total perception. The results must have been catastrophic.'

Pelham can imagine the catastrophe. Her imagination is salivating. She thinks of whole planets, whole star systems consumed by this plague. 'I see, I see.' Something hits her.

She turns, but the Doctor seems to be humming at the cylinder. 'So what stopped it?' she asks.