almost mesmerised by the weird motion.
After a few minutes the column slowed and stopped. Bilton and Stapley looked at each other. Where, or when had they gone?
'Look!'
Bilton followed Stapley's gaze to the screen.
They had a perfect bird's eye view of the Citadel.
'If that's a view from this ship,' said Captain Stapley, 'then the TARDIS
has turned into a helicopter.'
'Easy does it,' cried Angela in a voice more used to giving instructions about seat belts.
Another stone was lifted out and the hole was big enough to climb through to the Sanctum.
The Doctor peered into the rough entrance. An unearthly light shone on his face. He was nervous now. 'You don't have to come if you don't want to,' he said, looking at the Professor.
'I'll learn nothing waiting for you here.'
The Doctor was more than grateful. 'Good man.' He turned to the passengers. 'The rest of you stay put.'
The Professor and the Doctor hauled themselves up and disappeared through the opening.
The Doctor looked round the Sanctum. He was immediately aware of the sarcophagus in the centre, but went straight to where Tegan and Nyssa lay on the ground. He knelt beside them.
To his immense relief, Tegan began to stir. She groaned and opened her eyes. 'Doctor?'
The Doctor smiled.
'I've got such a headache.' She was stunned and disorientated and could remember nothing but a great explosion.
'Rest a while,' said the Doctor gently.
'They willed us to come here.' Nyssa was sitting up, fully recovered, her mind still mysteriously in tune with the alien intelligence.
'Who are they?' asked Professor Hayter. He had hardly moved since climbing down from the hole, so humbled and awed was he by the seraphic calm of the Sanctum.
'Look in the sarcophagus, Professor,' said the Doctor.
Both men walked slowly towards the marble casket in the centre of the chamber. They peered fearfully over the edge.
A thin stratum of vapour floated above the open repository. Below the mist a great cerebellum glowed and trembled.
'It's alive!' gasped the Professor.
They stood for a moment listening to the ethereal murmer, and watching the fibrilation of the huge viscera.
Professor Hayter had never seen a living organism like it before. 'What is it?' he whispered.
'An immeasurable intelligence,' whispered the Doctor, 'at the centre of a psychic vortex. All-seeing, all-knowing.'
Tegan and Nyssa gathered round. They all stood silently, just a little afraid.
'Why did it want me to destroy it?' asked Nyssa.
The Doctor thought for a moment. 'It didn't,' he replied. 'That's why it deflected your attack.'
He explained what must have happened at the moment of explosion. A massive burst of psychokinetic energy held back the rock thrown into the sarcophagus by Nyssa, hurled the two girls to the ground, and caused the beast summoned by Kalid to evaporate. So great was the power diverted to defend itself against Nyssa's physical assault, that every other manifestation of its energy was relinquished - even down to the plasmic body of Kalid. Now the force was expended.
'But why work against itself?' asked the Professor.
'Two aspects of the same personality?' suggested Nyssa.
'Jekyll and Hyde,' the Doctor nodded. 'The good and the bad.'
'The Professor was enthralled at such a perfect example of the co-existence of the Ego and the Id.
Tegan's interest was more pragmatic. 'Why should half the creature want to attack us anyway?'
The Doctor told her the worst. 'Its power is being used by the Master.'
Tegan and Nyssa were horrified to learn that the Doctor's supreme enemy was up to his old tricks, and exploiting the strange energy. But at least one part of the mighty intelligence in the sarcophagus had offered itself as their champion.
Nyssa tried to describe the force that drew them into the Sanctum and ultimately destroyed Kalid's monster, but no words of hers could convey that feeling of irresistible gravitation.
'How did you get in?' asked Hayter.
'The wall just opened.'
'Part of the benign intelligence must have triggered a hidden mechanism.'
'Did the same thing happen for you?'
The Doctor explained how they had broken down part of the wall.
'Where?' asked Tegan, surprised.
Hayter ran across to where they had made their entrance. 'The blocks have been put back!' He ran his hands over the smooth stones. All evidence of their entry had been removed.
They were trapped.
At that moment the Doctor knew - as surely as Nyssa felt - that the power was returning. The passengers outside would not, of their own free will, have reneged on the Doctor. They must be acting under hallucination again. Once more the invisible power haunted the Citadel.
That part of the intelligence in the casket which sympathised with the Master's evil schemes was working against the Doctor and his friends, and had walled them up, helpless, inside the Sanctum.
Professor Hayter was the least anxious of the prisoners. With the passionate curiosity of an archaeologist exploring a Pharaoh's tomb, he examined the various artefacts in the chamber.
'Doctor, come and look at this.' The Professor held up a small doll-like object. 'Some sort of figurine.' He looked around him. There's another, and another ... Could they be votive offerings? In which case, this chamber might have some religious significance.'
'Let me see that.' The Doctor took one of the figures from Professor Hayter and held it gently in his hands.
The detail was perfect. It might have been a statuette of some Greek god, only the unnatural completeness of all its features could never have been achieved by any sculptor.
'The Xeraphin,' said the Doctor in a hushed voice.
'Who are the Xeraphin?' asked Nyssa.
'They were supposed to have lived on the planet Xerophas before it was devastated by crossfire in the Vardon-Kosnax war.'
Hayter gave a little cry. 'Please, Doctor. On top of everything else, not little green men from outer space.' But by now he was prepared to believe almost everything.
'There's nothing green aoout the Xeraphin,' the Doctor continued. 'The most highly developed creatures in the universe. Beings of immense mental power.'
As he examined the figurine he recognised the handywork of the Master. 'The Tissue Compression Eliminator,' he muttered.
'What's that, Doctor?'
'That little toy of the Master's. If he used it on you, your whole body would be compressed ... just like this.' And he held up the petrified homunculus.
The Professor could not understand how the Xeraphin came to be at large in the Citadel.
'They came from the sarcophagus,' explained the Doctor.
'But the thing in there is still alive, and there's only one organism,'
protested Hayter.
The Doctor, however, was at last beginning to understand the nature of the intelligence in the casket, and the energy in the Citadel.
'No wonder the animus is so strong,' he gasped. 'Apart from the Master's victims, the whole race of the Xeraphin is in that sarcophagus!'
During his flying career, Flight Engineer Scobie had frequently wanted to tell his superiors to get lost. When however, he saw the Skipper and First Officer
transported to oblivion before his very eyes he was appalled.
The plan had gone badly wrong. From his hiding place, Roger watched the Master scurry to and from the TARDIS, clutching various peculiar appliances. He had observed the man's temper become more and more frayed. He had finally watched him abandon the Doctor's police box, and laugh demonically as it vanished into thin air.
The idea had been for Captain Stapley and Andrew Bilton to travel with the Master and keep in touch with the TARDIS. Heaven only knew where they were now. Meanwhile the Master seemed quite happy without the Doctor's amazing machine. He collected a few more items and left the chamber.
Scobie had absolutely no idea what to do next. There was no way he could help Stapely or Bilton, so he decided to find the Doctor and explain that the Master was at large in the Citadel, and that the TARDIS
had disappeared.
He crept down the corridor keeping a wary eye open for the Master.
A familiar figure in airline uniform emerged from the shadows at the far end of the corridor.
'Angela!'
'Roger!'
'Where are the others?'
She didn't answer his question. 'I can't hold out much longer.' The girl was in a bad way.
Roger Scobie realised that the hallucinations had returned, and that Angela was fighting the dream world. 'Angela, don't give up now!' He tried to comfort her and encourage her resistance. 'You mustn't let go of your mind.'
But it was obvious the poor girl was having an enormous problem resisting the illusions. How lucky for the flight deck crew that the Doctor made them reject the induction effect at the outset.
Angela was amazed that Roger could hold back the world of unreality with so little effort.
Roger Scobie explained. 'The Doctor destroyed the illusion as soon as we landed. Even when the Plasmatons got hold of us ...'
'The Doctor!' she interjected. As if he had touched a raw nerve.
'Was the Doctor with you?' Scobie needed to find him at once and explain what had happened to the TARDIS.
'The Doctor ... Yes, I think so.' She was becoming vague and sleepy again.
'Did you break through the wall? Did the Doctor get into the Sanctum?'
Scobie buffeted her with questions.
'Yes.'
'Come on!'
They both hurried off down the corridor.
The hall was empty when they arrived. Roger guided Angela, as if she were a sleepwalking child, to the central rotunda.
'Angela, where did you break through?'
The girl struggled to remain conscious. 'Somewhere along here,' she answered dozily.
They continued along the line of smooth, morticed stone.
'This can't be it,' exclaimed Roger.
Angela caught her breath at the sudden stab of lucid memory. 'The power returned ...The wall v/as sealed!'
she blurted out.
'What!'
'I tried to stop them.' The recall of it distressed her.
'Come on!' cried Scobie. 'We've got to get him out.' He clawed at the unyielding blocks. 'The Doctor's our only link with the real world.'
'Roger!' Angela felt a sudden swell of hallucinogenic power. She was going under.
Roger did not hear her desperate appeal. 'It's no good. We'll have to go and find some tools ...' He turned from the wall. 'Angela?'
The young stewardess was walking, like a zombie, towards an incongruous Greek pillar at the far end of the hall. Roger tried to catch up with her. But he was hardly half-way before the Master appeared from behind the pillar.
Roger hugged the side of the rotunda. He could just see Angela reach the column and stand beside the Master. He heard the Master's cold commanding voice.
'Go to my TARDIS. I am the Master. You will obey me.'
Without a word the stewardess dutifully proceeded into the body of the pillar itself.
Scobie had no time to speculate on how Angela could walk into solid marble, since the Master was coming towards him. He sidled further around the rotunda.
The Master was placing his weird pieces of apparatus at regular intervals around the wall.
Roger wished there was some way of getting in touch with the Doctor.
It looked as if the Master had enclosed the Sanctum in a magic circle.
And if the Master's
magic was as spectacular as Kalid's, then anything could happen.
The Doctor stared at the throbbing entrail in the sarcophagus. He was overwhelmed at the enormity of what the Xeraphin had achieved. 'The whole race physically amalgamated into one organism, with one massive personality,' he declared.
At the same time another piece of the jigsaw fell into place. 'That was what the Master wanted at the centre of his TARDIS.'
'Why?' asked Nyssa.
'He must have exhausted his own dynormorphic generator.'
'Of course, the nucleus is the perfect substitute.'
'And infinitely more powerful.' The Doctor shuddered. The concentrated energy of the Xeraphin harnessed to the evil will of his old enemy was an apocalyptic prospect.
Nyssa shivered. 'The power is returning.'
They all looked at the sarcophagus.
'Can't you feel it?' she moaned.
They all sensed cold like the unnatural chill of a summer eclipse. A ghostly breathing filled the chamber. The power that had already restored the phantasms outside the Sanctum was now reconsolidating its presence at the centre of the vortex.