The beast lurched forward and the Doctor backed away around the altar, keeping his eyes fixed on the hideous apparition. With a deft movement he whipped the torch from his pocket and switched it on, directing the powerful beam straight into Koquillion's goggling eyes. The creature stopped again, blinded.

Warily the Doctor edged forward again. 'Perhaps I should remind you that the costume of Khakhuiljan Khakhuiljan was only worn by the most senior Didoi and on the most solemn ceremonial occasions,' he said in a low calm voice. was only worn by the most senior Didoi and on the most solemn ceremonial occasions,' he said in a low calm voice.

'And, flattered as I am that you should consider my demise to be such an occasion, I do not feel that you are a worthy executioner...' With a sudden movement the Doctor reached up and grasped the head by one of the sabre fangs.

He gave a sharp tug and the beast's huge head came away in his hand.

'Mr Bennett I presume...' the Doctor said wryly, keeping the torchbeam directed relentlessly into the startled grey eyes which stared at him in disbelief. 'Allow me to introduce myself... the Doctor!' He chuckled genially, but then grew solemn as soon as he realised that Bennett did not appreciate the joke.

The Doctor glanced inside the huge hollow head. 'A most ingenious little voice distorting mechanism, Mr Bennett. I congratulate you. I must admit that your entrance through the chamber was really quite dramatic- almost unnerving.' He put the heavy mask down on the altar, taking care to keep the torch full in Bennett's eyes while he studied his gaunt, bearded face. 'Well, Mr Bennet, I am intrigued to know the reason behind your elaborate masquerade,' the Doctor continued calmly. 'You see, I happen to know something about the Didoi and their civilisation and what I heard about recent events here made me suspicious.' The Doctor paused, his body alert and poised to react.

Bennett backed off a little, blinking his watering eyes and turning aside. 'Then you might as well know the rest, Doctor,' he replied hoa.r.s.ely, his voice still sounding a shade artificial even without the miniature device fitted inside the mask. 'I was forced into all this to save my life...'

The Doctor kept his eyes on the vicious talons gleaming at the end of Bennett's huge arms. 'To save your life? But from whom? Not from the Didoi I venture to suggest,' he said acidly. 'There is no more peace-loving species in the entire Universe.'

'From the crew of Astra Nine Astra Nine,' Bennett retorted savagely, needled by the old man's scornful tone and by his own helplessness in the glare from the torch. 'I killed a member of the crew. I was arrested and then the craft crashlanded here and I managed to escape. The killing had not yet been notified to Intergalax, so I knew that if I disposed of the rest of the crew I would be safe.'

The Doctor's eyes narrowed with contempt. 'Disposed of the crew?' he echoed. 'Of course. How convenient for you to blame their deaths on the innocent inhabitants of Dido.' The Doctor threw back his head and his mouth curved tightly downwards in a grimace of disgust.

Bennett ignored him. 'After we crashlanded here the inhabitants invited the crew to a kind of congress.' Bennett grinned and shook his head at the naivete of his victims. 'It was so ridiculously easy. I rigged a b.o.o.by trap using the craft's electrophase condensors. Then...' Bennett crossed two claws as if for good luck, '... just two little wires touched and the whole congress went up. The entire population of the planet and the crew.'

The Doctor's face was impa.s.sive and frozen. 'You are insane, Bennett. You ma.s.sacred an entire population just to save your own skin?'

'I saved the girl,' Bennett snapped. 'Vicki did not know what I had done. She was unaware I had even been arrested. She thinks the crew were killed by the aliens and that I survived. Neat idea, wasn't it! When we are picked up she will corroborate my story.'

The Doctor nodded gravely. 'And you masqueraded as Koquillion to make her feel threatened by the planet's terrible inhabitants.'

Bennett laughed. 'She came to rely on me to protect her from Koquillion, so I kept control over her.'

The Doctor shook his head, sickened by the warped logic of Bennett's story. 'And if your plan had succeeded you would have been safe,' he sighed. 'Your guilt would have been concealed for ever.'

Bennett stared directly into the Doctor's eyes, no longer affected by the brilliant beam of the torch. ' If If it succeeded?' it succeeded?'

he echoed scornfully. 'But, my dear Doctor, nothing has changed. Except that there are now three more people for Koquillion to dispose of...'

A claw suddenly flashed through the air knocking the torch out of the Doctor's hand and Bennett lurched forward, his cold grey eyes bright with ruthless purpose.

Ironically, he looked even more fearsome now without the huge head: the combination of human head with reptilian body and insect claws suggested some nightmare mutation from the secret laboratory of a demented scientist.

Mesmerised by the slashing talons cutting the air only centimetres from his face, the Doctor backed away, desperately trying to think of a way to defend himself. All at once he felt the edge of the altar in the small of his back.

With a croak of dismay the old man bent backwards over the ancient sacrificial slab, gaping wide-eyed at the loathsome hybrid figure looming over him in preparation for the kill...

10.

Behind the blind gaping rectangle of an empty window up on the terraces, Barbara, Ian and Vicki had watched the nightmare figure of Koquillion crossing the shallow crater and entering the tunnel leading to the entrance to the Hall of Judgement. By the weird light of the three moons and against the fantastic wasted landscape the monster had looked like something out of a dream.

'Well, we certainly can't risk going through that way,'

Ian declared.

Barbara grinned weakly. 'I'm so glad you said that. I don't think I could face another confrontation with Mr Koquillion.'

Vicki shuddered. 'Nor I.'

Ian looked worried. He had forgotten all about the terrifying obstacle course of narrow ledges, gates made of knives and the fiendish b.o.o.by trap of moving walls which lay between them and the safe haven of the police box. Nor was he entirely convinced that the sand monsters-if there were any more of them-were quite so harmless as Vicki and the Doctor had claimed.

'Not only that,' he murmured, 'the Doctor and I came out that way and there's an awful cave with a ledge only six inches wide high up along the wall. I'm not sure I could face it again, especially with you two in tow.'

Barbara bristled indignantly. 'What do you mean, us two us two in tow in tow?' she demanded, nudging Vicki for moral support.

'Just you wait, Ian Chesterton. We girls aren't so useless as you boys like to think!'

Ian was about to describe the knives and the moving slab but then decided not to mention them, just in case they were forced to take that route after all. 'Come on, you two, we've got to look for another way through to the TARDIS,' he said with artificial eagerness to boost morale.

He turned to Vicki, who had hardly said a word since they had left the wreck. 'Vicki, you don't know of any other ways into the mountain, do you?'

Vicki shook her head. 'Bennett told me never to stray far from the Astra Nine Astra Nine. He said Koquillion's people would most likely kill me.'

Ian exchanged bleak glances with Barbara. 'Any suggestions?' he asked gloomily. 'I don't suppose there's any chance we could break into the tunnel up on the ridge, Barbara, the one Koquillion blasted to bits?'

Just then Vicki's body tightened like a drumskin.

'Look...' she whispered, staring across the crater towards the huge dark bulk of the silicodon's corpse.

They saw the two tall silver figures striding gracefully into view over the lip of the crater. The figures stopped and turned to one another. Then they turned and seemed to stare at the tunnel mouth. Finally, they set off round the edge of the crater towards the tunnel with long loping steps.

There was an awed silence.

'What the d.i.c.kens are they?' Ian gasped eventually.

'Those are the silver things that came into the wreck while you were looking for the Doctor and Bennett,'

Barbara gabbled in her haste to explain. 'Don't you remember? I caught a glipse of one when we were outside while the Doctor was having his little talk with Vicki.'

Ian stared open-mouthed at the shimmering creatures.

'But what are are they?' he asked Vicki. they?' he asked Vicki.

But Vicki seemed to have withdrawn even more into herself, like a child trying to make something nasty disappear simply by refusing to look at it. She seized their arms. 'We must get away. They will kill us!' she said.

But Ian and Barbara were so fascinated by the ghostly figures that they resisted Vicki's efforts to persuade them to flee. Suddenly, without warning, Vicki broke away and ran off into the depths of the ruin.

'Where is she going?' Ian muttered, hurrying after her.

'Vicki, come back here! Vicki!'

Barbara waited by the gaping hole in the stone wall, watching the strange figures pause by the entrance to the tunnel into which Koquillion had disappeared. She felt her skin creep as the figures stared around and seemed to look straight at her with their luminous green eyes, though she was fairly sure they could not see her in the shadows. She sighed with relief when at last they turned and vanished into the base of the cliff. She listened for some sign of Ian and Vicki returning, but the musty ruin was deathly quiet.

'Ian... Are you there?' she called, straining to see into the dusty blackness.

There was no reply.

Stretching out her hands in front of her, Barbara inched her way into the void with hammering heart and trembling limbs. The walls of the ruin felt powdery and her searching hands sent a fine choking dust into the air which stuck to her bone dry throat. She stumbled blindly through echoing empty chambers deeper and deeper into the mountain, croaking Ian's name over and over again. Eventually she heard m.u.f.fled voices in the distance. It was hard to make out what they were saying.

'Try to reach up...' Ian seemed to be telling Vicki.

'But I can't move...'

'Try to press your feet against the sides and use your back to lever yourself up...'

Then there was a terrible scream.

'What's happened? Where are you?' Barbara shouted, trying to orientate herself and decide which direction to take.

Again there was no reply.

With mounting panic Barbara pressed on. Gradually her eyes grew more accustomed to the darkness and she discovered that there was a very faint glow from veins of some kind of fluorescent mineral in the rock which gave a faint light and enabled her to see just a little without being able to distinguish much detail. As far as she could tell, the chambers were circular and connected by short tunnels some of which were blocked by stone shutters. Several of the chambers seemed to have collapsed and were blocked by fallen rock, and treacherous cracks and chasms lay like deliberate traps along the way. Frequently she stopped and called out, torn between wanting to be heard by her friends and avoiding giving herself away to whatever monstrous horror might be lurking in wait in the darkness. But there came no rea.s.suring answering shouts, nor even any cries for help or of warning. Ian and Vicki seemed to have disappeared without trace.

Eventually Barbara found herself standing on a kind of wide ramp sloping sharply downwards. She hesitated, unsure whether to venture on down the ramp or whether to turn round and gamble on being able to retrace her route to the terrace and then try another route altogether.

Something stirred in the darkness above and for a moment Barbara thought it was Ian and Vicki. She turned and was about to call out to them when something about the noise froze her jaw. She pressed herself back into the alcove leading to the last chamber she had pa.s.sed through and listened. The slow dragging movements were repeated in short regular bursts, as if a heavy weight were being dragged down the slope. Barbara's voice was a frozen lump in her throat. She forced herself backwards into the chamber.

But before she reached it she heard a sudden grating sliding noise and her back came up against a solid barrier of stone as a shutter droped down sealing off her escape.

Quaking with terror, she listened to the dry rasping approach of the invisible horror as it advanced relentlessly down the ramp towards her, rustling and crackling like the branches of a gigantic desiccated tree.

Ian's spine was racked with painful spasms as he worked his way down the slightly funnel-shaped shaft bracing his feet and back against its almost vertical sides. He could hear Vicki's pitiful moans rising out of the darkness below him and he scarcely dared imagine what he would find when he finally reached her.

He bitterly reproached himself for failing to catch her in time to save her from falling into the hole gaping in the ramp. He had not even considered the problem of how they were to get out of the shaft again. Suddenly the shaft narrowed until he could barely squash himself into it with his bent knees up against one side and his back against the other. Something soft touched his hand and he uttered a yelp of fright.

'It's all right. It's me!' said Vicki's m.u.f.fled voice from underneath him. 'I'm completely stuck.'

'Are you hurt?'

'No... just a little dazed and rather shaken.'

Ian wiped the sweat out of his eyes, though the air was quite cold and he shivered.

'There's a hole in the bottom here,' Vicki reported.

Ian did his best to raise his body a few centimetres to give her a little more room. 'A sort of drainage thing perhaps,' he suggested, wondering how on earth they were going to climb out.

'And there are some bones.'

Ian swallowed the layer of sand and dust coating his parched throat. 'Bones? What sort of bones?' he croaked.

There was a brief rattling noise beneath him.

'Animal bones... or human bones.'

Ian thought for a moment. 'How big is the hole?' he asked, an idea of loathsome horror occurring to him.

'About forty centimetres across.'

Ian forced a cheerful laugh. 'Oh good, no danger of slipping through then.'

'The edge keeps crumbling away, Ian.'

There was a pause.

'You mean the hole's getting bigger?'

'Perhaps this is some kind of trap,' Vicki murmured faintly.

Ian felt around him. 'Or a burrow,' he said grimly.

'A burrow? What for?'

'I'm not stopping to find out!' Ian tested the brittle sandstone sides of the funnel. 'Can you reach your arms around my waist, Vicki?'

Vicki tried. 'Yes, just about.'

'Right. Then hold on tight and try to use your knees to help...' Ian told her, starting to manoeuvre himself back up the conical shaft.

Vicki's additional weight was crippling, but they made slow progress despite the constant crumbling of the shaft walls. At last after a hard struggle they managed to reach the wider section of the funnel and paused to rest a moment.

'What about Barbara?' Vicki panted.

'I just hope she's had the sense to stay put,' Ian gasped, trying to ma.s.sage his numb knee and ankle joints.

'This is all my fault, Ian. I shouldn't have panicked,'

Vicki confessed in an embarra.s.sed voice.