'No, I mean that horrible shrieking.'

They lay there listening to the agonised howls.

'I think it must be the end for our arenicolous friend,'

the Doctor said quietly.

Ian scrambled to his feet and started dragging the Doctor after him. 'Come on, Doctor, Barbara could be in danger!' he urged.

They emerged from the tunnel, blinking in the fading light, and stared in horrified revulsion at the huge melted and charred head writhing among the boulders.

'I'm not sorry to see the end of that thing,' Ian said, coughing from the acrid smoke curling off the creature's rubbery flesh.

The Doctor suddenly looked rather sad. 'Actually the poor beast was quite harmless,' he murmured. 'I had forgotten the silicodon, a species found only on Dido and a planet called Sokol in one of the Willoughby galaxies.'

'No sign of Barbara anywhere,' Ian said anxiously, craning up at the ridge towering above them.

Something caught the Doctor's eye. 'Look!' he cried, indicating a small figure struggling towards the wreck.

'That's not Barbara.'

The Doctor's face fell. 'No, it is not.' He turned to Ian.

'Then who is it? Come on Chesterton!'

They set off at a cracking pace in pursuit.

Vicki flung down the water bottles and fixed Barbara with a look of utter hatred. For a few seconds she was speechless.

Barbara stood near the hatch, completely nonplussed by Vicki's reaction to her quick thinking. 'Vicki, you've had an awful shock...' she began.

'You killed Sandy!' Vicki screamed at her. 'Why?

Whatever made you do such a terrible thing?'

Barbara hesitated, baffled by the girl's extraordinary question. 'But Vicki... the thing was almost on top of you!'

'How could could you!' blazed Vicki, tears running down her dirty face. 'Sandy only wanted some food.' you!' blazed Vicki, tears running down her dirty face. 'Sandy only wanted some food.'

'But it was going to attack you.'

'Sandy only eats... only ate ate plants and insects. I trained him to come here for food.' plants and insects. I trained him to come here for food.'

Barbara spread her hands helplessly. 'But, Vicki, I couldn't have known that could I? I thought you were in terrible danger.'

Vicki picked up the containers and shoved past Barbara into the hull. 'I shouted... I shouted to you, but you did not listen,' Vicki accused.

Barbara followed her inside. 'Vicki, all I could see was those awful jaws, and it was making such a horrible noise I just ran for this thing and fired.'

Vicki flung the containers onto the makeshift table and rounded on Barbara, her eyes livid with anger and hurt.

'He was my only only friend and you friend and you killed killed him!' she sobbed, collapsing onto a duct casing. him!' she sobbed, collapsing onto a duct casing.

Barbara looked at the Very pistol she was holding and then at the broken figure of Vicki, utterly at a loss what to do. Then a sudden movement outside made her spin round with a gasp of fright. She levelled the pistol at the hatchway and watched the two long thin shadows approaching across the sand outside. Another sharp movement behind her caused her to swing round again to see that Vicki had stood up and was pointing at the open hatch in panic. Before Barbara had time to turn back to the entrance, she heard footsteps on the metal edge of the hatchway.

'I think you have already used up that cartridge, my dear!' cried a familiar voice.

'Barbara!' cried another familiar voice.

Scarcely daring to believe her ears, Barbara slowly turned. 'Doctor... Ian... I thought you were both dead!' she burst out, her voice wavering with grat.i.tude and relief.

The Doctor shook his head wearily. 'People are always trying to kill me off,' he complained, smiling and easing the gun out of Barbara's hand. 'But I never felt better in my life, my dear.'

He glanced over her shoulder at Vicki's tearstained face and his keen eyes lit up with interest. 'And who do we have here?'

The still, dead air in the labyrinth of caverns was disturbed by a harsh grating sound. The rectangular panel, which the Doctor had just been examining in the rock face above the ledge, swung slowly open on juddering hinges. There was a dry scratching noise and then the tall bristling figure of Koquillion emerged onto the ledge hissing and rustling its antennae in the gloom like some gigantic nightmare gra.s.s-hopper. Its globular red eyes burned at the end of their stalks as it stared along the ledge in the direction of the low tunnel leading outside.

A dull opalescent light played over the ledge from some source beyond the mysterious doorway, and in the layer of dust and sand on the rocky shelf it illuminated a distinct heel print from the Doctor's boot. Koquillion bent forward to examine the print and noticed a vague trail of two sets of footprints leading towards the tunnel. The creature's breath hissed with pent-up menace as it traced the outline of the print with its scimitar claw. Straightening up, Koquillion turned and prodded a sequence of points on the embossed surface of the panel. With a click and a grating shudder the panel ponderously swung shut flush against the rock face. Koquillion stalked off along the ledge following the footprints with awkward birdlike strides.

After a while the panel in the rock wall grated open a second time. Two tall, slim figures appeared on the ledge and slowly stared around themselves before closing the panel by the same method as Koquillion. The figures had long heads tapering to narrow jaws set on slender necks.

Their features, if they had any, were mere pale smudges in the darkness - flat and smooth with faintly sparkling flecks on the skin. Only their eyes showed clearly as large greenish gleams, almost perfectly circular.

Their lithe bodies were encased in tightly fitting single-piece suits made of a mirror-bright silver material which incorporated supple boots and a kind of balaclava headgear. From the shoulders hung short multilayered mantles made of the same material. The beings made no sound at all. Even their breathing, if indeed they did breathe, was inaudible. They turned to one another in a kind of graceful slow-motion and seemed to communicate without speech.

Then they strode off along the ledge, their wiry bodies relaxed but alert, gliding towards the cavern entrance like silver wraiths bent on some secret purpose...

7.

Night had almost fallen. In the wreck of Astra Nine Astra Nine the power cells were still producing just enough energy to provide reasonable illumination in the hull compartment. the power cells were still producing just enough energy to provide reasonable illumination in the hull compartment.

Outside, the air was already growing chilly, but inside the wreck it still felt hot and stuffy. The Doctor was sitting on the duct casing with Vicki, while Barbara and Ian hovered tactfully in the background.

The Doctor had been trying to comfort Vicki, chatting gently away like a favourite uncle. 'So you see, my dear child, in a few hundred Earth years' time there will be no night at all on this planet because Dido will be positioned exactly midway between its two suns... Here, take this and blow your nose.' He handed Vicki his rather grubby handkerchief. 'And give that pretty face of yours a wipe too. If you will excuse me saying so, you do look rather a mess at the moment!'

Vicki hesitated. Then she took the handkerchief, cleaned her grimy face and blew her nose. She managed a wan but grateful smile. 'Is that better?'

The Doctor glanced round at Ian and Barbara, preening himself with his success. 'Much better.'

Ian took another sip of brownish water from a mug and brandished the signal flare pistol he had been examining.

'Cheer up and stop worrying,' he cried heartily. 'If this Koquillion chap shows his ugly face here again we'll make a mess of it for him!'

But Vicki's smile vanished as abruptly as it had appeared. 'You must not talk like that,' she gasped. 'I keep trying to explain why Bennett and I have to obey Koquillion. He has protected us against the others all this time...'

The Doctor fixed Vicki with his cold, piercing gaze. 'My dear child, have you seen seen any of the others?' he asked sharply. any of the others?' he asked sharply.

Vicki hesitated again, almost as if she were tempted to conceal something from them. She shook her head firmly.

'No I have not and I hope I never will.' All at once she sprang up and faced them like an animal at bay. 'You will spoil it! I know you will. You will spoil everything!' she shouted, pointing accusingly at Ian who was still brandishing the gun.

The Doctor rose and took Vicki's hands in his. 'It's all right, Vicki, we would not wish to jeopardise your safety,'

he a.s.sured her quietly. 'I promise you that we shall not interfere with the rescue. But I should like to have a chat with your Mr Bennett because I think I may be able to help you both. Would you be kind enough to take me to him?'

Vicki's suspicious gaze darted from one to the other.

She seemed to have regained a streak of steely defiance.

She shook her head vehemently. 'The rescue craft is on the way. It will arrive soon. It is going to take us back to Earth.

Don't you people understand?'

Barbara stepped forward. 'Now, listen, Vicki, you've been here a long time,' she began in her straightforward cla.s.sroom manner, 'and I don't think you're facing up to what Koquillion might...'

Vicki thrust her face into Barbara's with unexpected ferocity, her eyes blazing with resentment. 'Yes, that is true. I have been here a long time,' she shouted, her lip curling. 'I know what has been going on. But you people just walk in here and a.s.sume that you are going to take control. But we don't need you! You will only ruin everything.'

Vicki darted up to the Doctor and then to Ian, her frail body taut with belligerent independence. 'It was all right here before you arrived, it really was. And the Seeker Seeker is coming. n.o.body invited you here! n.o.body!' Shaking with anger, she turned her back on them and leaned over the radar installation. is coming. n.o.body invited you here! n.o.body!' Shaking with anger, she turned her back on them and leaned over the radar installation.

The Doctor glanced gravely at Barbara and Ian and silently motioned them out of the compartment. His two companions looked at one another rather reluctantly. The arid dust outside did not exactly look inviting. However, they nodded meekly and quietly went out through the hatchway into the night, taking care to keep close together.

The Doctor cleared his throat and joined Vicki at the radar scanner. 'Most interesting... An X-ray scanning system and a very advanced version too,' he remarked, genuinely surprised, and anxious to avoid broaching the subject of their recent argument. 'The prototype systems used ordinary X-rays and were far too hazardous for general application. However these accelerated axion systems can be most satisfactory. Perhaps Mr Bennett might allow me to take a little look at it later?'

Vicki kept her back to him and said nothing.

The Doctor chose his words with the utmost care.

'Vicki, I listened to what you said and I understand the way you feel; but I suspect that you didn't really mean all that about us wanting to take control, did you?'

There was a brief pause and Vicki bit her lip and shook her head.

The Doctor sat down agan. 'Please come and sit down, Vicki. We mean you no harm. We want to help if we can.'

Vicki turned. 'Bennett says that when we reach Earth we must explain what they did to us here. He wants this planet obliterated. He says that Koquillion must not be allowed to escape punishment for what he did.'

The Doctor sighed, his face etched with perplexity and concern. 'Well, I agree with Bennett about Koquillion at least,' he replied earnestly. It was clear that he was deeply troubled and puzzled by the inexplicable change in the behaviour of the planet's inhabitants since his previous visit. 'But as you are aware, I know a thing or two about Dido so don't you think there is a chance that I might be able to help Mr Bennett deal with the situation a little more effectively?'

Vicki gazed at the Doctor, her face calmer and her eyes disconcertingly direct and searching. The old man was impressed by her cautious dignity. she gave a slight smile and nodded.

The Doctor beamed. 'Splendid.' He stood up briskly.

'Now, let me talk to Mr Bennett and let's see if we can sort something out. I promise I shall listen to what he has to say.'

Vicki offered him her hand. 'Come along, I'll take you to him.'

The Doctor clasped her thin hand between his own with a warm smile of rea.s.surance and Vicki led him through the interior hatchway. The Doctor took a close interest in the complicated tangles of debris cluttering the intermediate compartment, muttering mysteriously to himself as he identified various items of equipment which lay twisted and scattered around them.

'Thank you, Vicki, I can manage now...' he said, releasing her hand, 'Why don't you pop out and keep an eye on Barbara and Ian for me? I don't want them wandering off and getting themselves into hot water.'

At first Vicki grinned, fascinated by the Doctor's quaint manner and his odd expressions. Then her face darkened.

'Barbara...' she did not finish her sentence.

The Doctor frowned and wagged his finger. 'Now, now, Vicki. You're not giving poor Barbara much of a chance,'

he scolded.

'She killed Sandy.'

The Doctor grimaced and nodded. 'If I were Barbara I should have done the same. She had no idea that the poor beast was harmless.'

Vicki shook her head adamantly. 'No, you have not the sort of face that... that kills...'

'And Barbara has?'

Vicki remained silent.

'Barbara believed that you were in danger, Vicki. After all, Sandy was not a very benevolent-looking pet, was he?'

Vicki tried to resist the Doctor's gentle but persuasive argument. 'No, I suppose not,' she was forced to admit eventually.

The Doctor put his hands on her shoulders. 'Believe me, Sandy had a much quicker and more merciful death than the one which awaited him through starvation and cruel thirst,' he said quietly. 'Please try to understand what Barbara did and why. Will you try and do that?' he asked gently. 'For me?'

Vicki thought for a moment, biting her lip at the painful memory of Sandy's death. But at last she smiled and nodded. 'Very well.'

'Thank you,' the Doctor murmured, pushing her gently but firmly through the hatch. Then he turned and clambered through the maze of wreckage towards the shutter leading to Bennett's compartment.

He found it slightly open. 'Mr Bennett?' he called.

There was no answer.