'Come on! We've got to find them!' cried the Doctor, rushing from the control room.

Turlough ran, panic-stricken, down one long corridor after another, terrified that the creatures he had disturbed in the hidden chamber were after him.

He stopped. There at the bottom of the staircase was the Doctor's police box. Safety at last.

The control room was empty the perfect opportunity.

He would steal the TARDIS.

He poured over the console. With a little experimentation he could surely make the thing work.

'You will not be able to operate the TARDIS!'

The Black Guardian glowered from the scanner screen.

'I can work it if you show me how!' shouted Turlough defiantly. 'Then the Doctor will be trapped and I can escape. Isn't that the agreement?'

'Do you think I have controlled you merely to p.r.i.c.k the flesh of this presumtuous Gallifreyan?'

Turlough was near despair. 'What more do you want of me!' he pleaded.

'The friend of the Doctor's is at present on the ship in two aspects. You must find the Brigadier who travelled with the Doctor's companions.'

Turlough slumped despondently over the console. But his evil master would condone no weakness. 'The co-existence of the Earthling is hazardous to our plans. The two Brigadiers must be kept apart.'

'But those creatures!' protested Turlough, thinking of the living corpses that by now must roam the ship.

'The mutants released from the dormition chamber threaten only the Time Lord!'

Suddenly, Turlough understood that the ship, the undead things from the chamber, the Brigadier, his own sabotage of the transmitter were mere elements of a master plan, the climax of a cosmic vendetta. With the Doctor destroyed, the bargain he had made, indeed his own life, would be worth nothing.

He gave a quick glance at the dematerialisation control.

Perhaps he could spiral the TARDIS out into time/s.p.a.ce, and free himself from the evil...

'Turlough!'

Even as the thought of escape came into the boy's mind he felt the pain in his forehead and the voice of the Black Guardian reverberated inside his skull. 'You will remain on the ship and witness the nemesis of the Doctor!'

It had not been a pleasant task dragging the cankered body up from the floor of the Laboratory, but the Brigadier was far too worried about the Doctor to feel squeamish. If only his old friend had kept his hands off that machine.

Following the instructions that issued from the shrunken head, the Brigadier positioned the decomposing body in one of the frames that connected with the regenerator. He obediently positioned the electrodes and, albeit reluctantly, switched on the apparatus.

The speed of the healing process astounded him.

'The energy repairs the depredation of the transmat capsule.' The Doctor sounded stronger already.

The Doctor? Brigadier Lethbridge-Stewart peered at the alien face reforming between the electrodes. 'You're not the Doctor at all!'

'I am Mawdryn.'

The Brigadier was angry at being fooled into helping the enemy. 'Where is the Doctor?' he shouted.

'I do not know.'

'You're lying.'

Mawdryn shook his head.

'Unless you tell me I shall turn off your life-support system.'

Mawdryn smiled sadly. 'It does not matter.'

'I imagine it matters to you if you die!' The Brigadier moved his hand to the controls of the regenerator.

Mawdryn stared at the Brigadier with such a look of pain and longing. For a moment the old soldier's mind went back thirty-five years to his first taste of action as a young lieutenant in Palestine, with his platoon badly shot up by terrorists, and he remembered the mangled conscript who screamed at the officer to take his rifle and kill him.

Mawdryn groaned. 'Without the energy only our shape will change.' He gave a deep sigh. 'Our endless voyage will never cease. We cannot die.'

The younger Brigadier moved cautiously through the ship.

As he paused at the junction of two corridors, there was a distant rustling which sent him darting into the shadows.

Round the corner came seven figures in wide flowing cloaks, which glided past within inches of where Lethbridge-Stewart was pressed up against the wall. He recoiled in horror as he glimpsed their terrible cowled faces.

'Stay here,' said the Doctor to Tegan as they reached the narrow turning to the laboratory. 'If your your Brigadier comes past, stop him.' Followed by Nyssa, he made his way up the pa.s.sage and into the laboratory. Brigadier comes past, stop him.' Followed by Nyssa, he made his way up the pa.s.sage and into the laboratory.

Both the Doctor and the Brigadier were delighted to see each other. 'Thank goodness you're all right!' cried the Doctor, who had never expected to track down the older Lethbridge-Stewart so easily. With one half of the duo under control they could avoid the Blinovitch Limitation Effect.

'Doctor! Over there!' screamed Nyssa, pointing at Mawdryn, who was still drawing energy from the regenerator. 'That's him him!'

With a sense of deep foreboding the Doctor walked over to the master of the ghostly vessel. The alien smiled coldly.

'I am Mawdryn. Welcome to my ship, Time Lord.'

'So it was you who stole the regenerator from Gallifrey.'

'Yes, Doctor. But time itself has punished us for the crime.'

'You modified that machine?' The Doctor looked at Mawdryn in awe. 'You created endless life for yourselves?'

'Endless torment!' Mawdryn's face twisted with physical and mental distress. 'Our bodies eternally renewed in a vile travesty of our former selves.'

The Doctor was appalled. 'You induced a perpetual mutation?' he whispered.

'So horrible,' replied Mawdryn bitterly, 'that we were exiled in this ship.'

'How were you able to come to Earth?'

'It is decreed; every seventy years, the beacons guide the ship to within transmat distance of a planet. While seven of our company sleep, one of us may leave the ship to seek help.'

But the Doctor knew, as well as Mawdryn, that there was no help; the red ship was destined to orbit eternally with its crew of mutants, their bodies spared from inexorable degeneration only by the power of the regenerator. But whether they continued to live in the luxurious and stabilising confines of the ship, or floated amoeba-like in the void of s.p.a.ce, they would never die.

'It is the Time Lords' curse!'

'The curse of your own criminal ambition,' answered the Doctor, sternly.

'The Time Lords could have helped us, but we were abandoned.'

'Time Lords cannot become involved.' The Doctor spoke as if the law was inviolate, yet it was a rule he had broken many times.

Mawdryn said nothing.

The Doctor turned away, unable to meet the mutant's gaze. He was trembling. Was this, he wondered, the ultimate coincidence? Had he been hounded, through time and s.p.a.ce, in despite of infinite improbability, to this fateful confrontation?

'Doctor!' There was a shriek from the corridor and Tegan came running in. She had spotted the seven mutants from the dormition chamber making their way to the laboratory.

'My brothers in exile,' explained Mawdryn, scornful of the Earthchild's fear. 'They need the regenerator.'

Tegan turned spitefully to Mawdryn. 'I always knew you weren't the Doctor!'

'Look out!' shouted the Brigadier, as, one by one, the seven undead, released unwittingly by Turlough from the chamber, entered the laboratory.

The seven years of sleeping had been a blessed respite from their torment, but it had taken a heavy toll of their substance. As if shamed by the presence of uncontaminated mortals, they gathered their cloaks over their rotting features, as, one by one, they joined themselves to the stolen machine.

'Who are they?' whispered Brigadier Lethbridge-Stewart.

'Scientists who tried to turn themselves into Time Lords,' said the Doctor. 'But it all went horribly wrong.'

'It is eternal agony!' cried Mawdryn. 'That is why we long for the ending.'

'These people...' Tegan stared, horrified, at the gasping mutants. 'They're immortal?'

'Yes. For what it's worth.'

The regenerator hummed noisily. Each mutant was growing stronger. The Doctor backed nervously away to the door.

'Doctor!' Mawdryn called. 'The life-force flows. Join yourself with us.'

'No!' shouted the Doctor.

'Give us the life-force from a Time Lord,' pleaded the leader. 'The abberation will resolve and our suffering will end.'

'Never!'

The Brigadier, Tegan and Nyssa were amazed to see the Doctor so afraid.

'For pity's sake,' begged the mutant. 'You cannot refuse.'

The Doctor turned his back on Mawdryn and his seven companions.

Even Tegan was upset by such coldness. 'Why can't you help them, Doctor?'

The Doctor rounded angrily on his companion. 'A Time Lord can only regenerate twelve times. I have already done so four times.'

'So?'

'Don't you see!' shouted the Doctor, desperate to escape from the laboratory. 'Eight of them. Eight of me!'

The silent eyes of the eight mutants never left the Time Lord. The Doctor felt paralysed by their desperate need.

'They want my eight remaining lives to end their mutation,' he whispered, white with anxiety. 'They want to take away my own regenerative powers!'

7.

Double Danger of the Brigadier Turlough searched nervously for the Brigadier who had come with Tegan and Nyssa from 1977. He was not convinced that the sleepers from the dormition chamber were as harmless as the Black Guardian claimed, and was anxious to avoid a second confrontation.

He darted behind a convenient piece of abstract sculpture. Someone - or something - was coming towards him. Turlough smiled as he spotted the dapper blazered figure walking slowly down the corridor. It was the Brigadier, all right; but this confident, strutting, military man was not the Brigadier that Turlough knew.

What was more to the point, neither did this - the younger Brigadier as yet know Turlough.

'h.e.l.lo, Brigadier!' Turlough stepped out in front of a startled Lethbridge-Stewart.

'Who the devil are you?'