Vicki pushed her back firmly. 'Do not move. Please stay there,' she begged. 'It might return any moment. You have no idea...'

If Barbara had known who the girl was talking about she would have retorted that she had plenty of idea. But she lay back on the pillow and ma.s.saged her throbbing temples. 'All right...' she murmured weakly. 'But who are you?'

'I'm Vicki.'

Barbara tried to smile, but winced with pain instead.

'Short for Victoria?' she asked.

Vicki looked blank. 'Victoria? No, not short for anything. Just Vicki.' She cast an anxious glance towards the partially closed shutter, then turned back to Barbara, a little calmer. 'Are you from.. You are not from the Seeker Seeker?'

she said hopelessly.

'The Seeker Seeker?'

'The rescue craft.'

Puzzled, Barbara frowned and gingerly touched her scratched and bruised face. 'Rescue craft? No, Vicki, I am from the... My name is Barbara,' she said kindly, managing a sort of smile.

Vicki seemed rea.s.sured. She wiped away her tears and returned Barbara's smile as she sat herself on the edge of the bunk.

Barbara was now feeling much more alert, despite her hammering headache. 'Tell me about this... this Koquillion,' she said.

Vicki glanced at the shutter. 'It... He just keeps us here.'

'Us?'

'Bennett and me. There's a rescue craft on its way here.

But Koquillion does not know about that!' Vicki added hastily. 'But he will find out eventually, I know he will. He always does.'

Barbara pushed herself into a semi-sitting position and put out a comforting hand. 'Why does Koquillion keep you here?'

Vicki tried to pull herself together. 'They killed all our personnel, except for Bennett and me... When we crashlanded here we made contact with them... One night they invited us to a sort of council meeting... I had a fever or something and I stayed here in the wreckage... I remember waking up suddenly and thinking it was a thunderstorm but it was... it was an explosion...' Vicki shuddered at the traumatic memory and fell silent for a while overcome with grief. 'But Bennett survived... The only one... He dragged himself back to the wreck... It was days before I recovered and then I found him... Bennett cannot walk. I look after him. We just wait and wait. We have been waiting so long and still no rescue... And I thought you...' Vicki was overwhelmed by silent heartrending sobs.

Barbara sat herself up and put her arms around the girl's heaving shoulders. 'Vicki, I don't understand. If Koquillion's people killed the rest of your crew, why don't they kill you and Bennett? It doesn't make sense.'

Vicki shrugged and shook her head in despair. 'We don't know. We just don't know.'

Barbara bit her lip while she tried to understand what Vicki had been telling her. 'You say you crashlanded here.

Where were you making for?' she inquired gently.

Vicki stood up, the tears now running freely down her pale cheeks. 'My father was taking me to... My father was...'

She crept slowly away from the bunk and leaned her head against the metal panelling of a huge duct which ran the length of the compartment.

Quietly, Barbara swung her legs over and sat up on the edge of the bunk, her concern for Vicki making her forget her injuries and the pain in her head.

Vicki struggled to recover herself. 'Your craft... Is your craft still here?' she asked eventually, turning with a trace of hope in her eyes.

Barbara nodded. 'Yes, yes, I think so,' she said uncertainly.

Vicki took a few faltering steps towards her and then stopped dead as if she had walked into an invisible barrier.

'I remember now, KoquiIlion told me. Perhaps you heard him? They killed the others, Barbara. They killed them.

Your friends up there have been buried alive.'

Barbara uttered a little gasp, as if a veil had suddenly been lifted from her eyes.

'Koquillion...' she breathed, reliving her nightmare encounter outside the tunnel and feeling her injuries again.

Abruptly she realised that if what Vicki said was true, then she too was stranded, a helpless castaway on an alien and inhospitable world.

The Doctor groped around his feet and finally located the torch. 'I don't care for Wagner very much,' he joked, fiddling in the darkness to fix the loosened connection.

'Especially when arias are sung like that that!' At last he got the thing working again and shone the beam over Ian's shoulder.

Ian remained silent, watching the play of the torch on the sinister tunnel ahead and nervously licking his lips as he waited for the unearthly din to recur, or worse, for whatever had caused it to burst out of the shadows and attack them.

'I just cannot understand it you know,' the Doctor chattered, noticing that the tunnel appeared to broaden out a few metres ahead of them. 'Violence was totally alien to the inhabitants of this planet in the past.'

Ian uttered a grim chuckle. 'People's ideas change, Doctor. I mean, every new leader...'

The Doctor shook his head, waving the torch to and fro at the same time. 'No, no, no, Chesterton, the Didoi had the best of reasons for avoiding death and destruction. The last time I was here the entire population numbered only a hundred or so.'

Ian's eyebrows shot up in surprise. 'But that's just a handful,' he muttered, thinking that as far as he was concerned just one of the fearsome creatures was quite enough.

The Doctor noddd solemnly. 'Yes, the mere remnant of a once magnificent civilisation,' he sighed regretfully.

Ian stared in disbelief at the word civilisation.

But the Doctor barely noticed him. 'You see, this is a very unusual planet,' he went on. 'It orbits two stars, not just one like the Earth, and to make things even more complicated the two stars are in orbit around each other.'

Ian looked even more incredulous.

'It is known as a rotating binary,' the Doctor continued, warming to his theme. 'But the gravitational effects make the planet's...o...b..t extremely eccentric like a figure-of-eight.

When Dido reaches a certain critical position, the combined heat, light and radiation from its two suns become so intense that the vegetation is burnt up and the seas evaporate. The inhabitants are forced to retreat underground in order to survive.' The Doctor pondered silently for a few minutes. 'The critical period lasts for the equivalent of hundreds of your Earth years. Very few Didoi survive each cycle, I'm afraid.' The Doctor turned to Ian with a wan smile. 'So you see, my boy, peaceful cooperation means everything to them. Without it, they would become extinct.

Ian was about to remark that extinction would be no bad thing, but he decided that it was no use arguing. 'Are you happy to go on, Doctor?' he inquired considerately.

The Doctor shrugged. 'Me? Go on? Don't ask me, Chesterton. You You were the one who stopped.' were the one who stopped.'

Ian took the torch from him. 'Yes, Doctor, and you you were the one who dropped the torch!' were the one who dropped the torch!'

Holding the torch out in front of him like a shield, Ian led the way further along the narrow, buckled defile which gradually began to widen out into a vast, black, echoing cave. Ahead of them they became aware of a heavy m.u.f.fled thumping and dragging sound. Exchanging wary glances, they advanced into the gigantic dark vault and a new sound, even more menacing, sent the hair p.r.i.c.kling on the backs of their necks. It was the sound of a ma.s.sive pair of lungs expanding and collapsing with ominous and relentless power, like a steam hammer in a foundry.

Barbara smiled gratefully as Vicki bandaged her injured hand. The ointment Vicki had applied to her face had soothed the bruises and scratches and she was already feeling much better.

'I should have attended to this straight away instead of behaving so pathetically,' Vicki said shyly. 'I'm ashamed of myself. I don't know what you must think of me.'

'I'm very grateful to you,' Barbara told her sincerely.

'I'm jolly lucky to escape so lightly.' She tried to move her arm, but the shoulder was stiff and swollen. 'It's mainly my arm. I must have wrenched it when I grabbed hold of the tree to break my fall. I hope it isn't dislocated.'

Vicki finished the bandage and got up to put away the medical kit. 'I wonder if Koquillion has gone yet?' she murmured, glancing at the shutter.

Barbara looked round, puzzled. 'Surely we would've seen him.' There appeared to be only two hatches in the compartment.

Vicki pointed to the internal shutter. 'The hull is split wide open through there,' she explained. 'There is a way out through where the intermediate airlocks were.' She gestured at the lash-up of communications equipment and at the makeshift table and bunk. 'After the crash we set up some essential things here because the power cells are in this section. Then, after the... after the explosion I tried to make living s.p.a.ce for myself and for Bennett.' Vicki trailed into silence, twisting her hands in anguish.

'Where were the proper living quarters?' Barbara asked as tactfully as she could.

'In the sphere.' Vicki gestured beyond the bulkhead. 'It broke off on impact. Our engineers cut a way out. There was a reactor leak and it's all contaminated now.'

Barbara stood up slowly and took a few faltering steps to test her legs. 'Well, no broken bones at least,' she smiled.

Vicki said nothing but just stared at the bulkhead which led through the debris to Bennett's compartment as if waiting for Koquillion to emerge.

'What are the others like?' Barbara asked, trying to prompt Vicki to talk about her fears.

'Koquillion is the only one we ever see. They live quite near, I believe, somewhere in the caves. They have to because of their suns or something. It is something to do with the radiation but I don't really know... and the silver things...'

'Silver things?'

Vicki shook her head sharply, as if she did not want to discuss it. 'I have glimpsed them sometimes, just for a second... ' she said reluctantly. 'Like statues. Just for a second.' She crossed to the bulkhead and opened a small panel to put away the medical kit.

Barbara caught sight of a large pistol in the locker. 'Isn't that a gun?' she said, a vague and reckless idea flitting across her mind.

Vicki took it out to show her. 'It's not a weapon,' she explained. 'It fires a signal flare. I keep it ready.'

Barbara recognised it as an extremely sophisticated version of the Very pistol. 'For the rescue craft?'

Vicki nodded and put the pistol back in the locker. 'Our power cells may not last to operate the radio beacon,' she admitted. 'I just hope they find us before it is too late.'

'When are you expecting them to arrive?'

Vicki just shook her head. It was as if her experiences after the crash and the ma.s.sacre of the crew had numbed her spirit and drained all the fight and energy from her mind and body.

Barbara desperately wanted to help, but she was beginning to realise that she might find herself depending on the rescue craft too. 'Perhaps it will come soon', she said brightly.

Vicki turned on her. 'But there is always Koquillion!'

she shouted. 'He could stop us... He could keep us here forever!' She frowned suspiciously. 'Why are you staring at me like that?' she demanded savagely.

Barbara was taken aback. 'Like what?'

'You're sorry for me,' Vicki spat, advancing as though to attack Barbara. 'There is no need, do you hear? No need! I am perfectly all right. It does not matter to me whether they come or not. I shall be all right!'

Barbara retreated. At first she was dumbfounded, then she guessed that Vicki's outburst was a kind of attempt to a.s.sert her independence and also a reaction to the bitter disappointment of discovering that Barbara was nothing to do with any rescue mission.

Before Barbara could say anything, Vicki suddenly went as taut as a bowstring. Beyond the bulkhead they heard the sound of laboured movement through the tangled wreckage. Leaping forward, Vicki pushed Barbara down onto the bunk and flung the blankets over her so that she was completely hidden. Then Vicki hastily retrieved some of her scattered rock specimens and sat down with them at the table.

Next moment the shutter panel was thrust fully open and Bennett stumbled into the compartment. He stood staring at Vicki, swaying jerkily on his injured leg. 'He has gone...' he said hoa.r.s.ely, clutching at the radar scanner for support. 'He tried to trick me into telling him things but I did not Vicki. I did not tell Koquillion about the Seeker Seeker.'

Vicki nodded and tried to smile approvingly.

Bennett lurched a few paces nearer. 'Koquillion told me about some strangers up on the ridge... The people in the cave... He killed them all, Vicki... You and I must help each other now... We must cooperate and take care of...'

Vicki jumped to her feet. 'No, Bennett! Koquillion has not killed all of them!' she cried.

The blankets were flung aside and Barbara manoeuvred herself upright in the bunk. Bennett swung round and gaped at her as though unable to believe his eyes. Then he uttered a menacing, almost primitive cry. Raising his huge fists in the air, he staggered towards the bunk. Barbara shrank back against the hull, her bruised face blank with terror.

5.

'Do be careful, Chesterton!'

'Be careful, Doctor!' Ian called back. 'It's getting even narrower.' Ian was leading the way along a steadily narrowing ledge which ran high up the side of the huge cavern. Beyond the crumbly edge there yawned the dark abyss, and far below them the torchbeam picked out the jagged boulders and razor sharp pinnacles which pierced the sandy floor. And still the monstrous breathing and burrowing sound echoed all around them, but they could not identify the source. It was as though the mountain itself was a living thing that had swallowed them up; the noises they were hearing were its heartbeat and the working of its mighty lungs.

Suddenly part of the ledge broke away and fell clattering into the darkness. The Doctor lost his footing and started to slip, his fingers scrabbling uselessly at the rock face.

Luckily Ian reached back in time and helped him onto surer ground. They paused for a moment, panting and wiping the sweat from their faces.

'Take it easy now, Doctor,' Ian warned.

'Thank you, my boy.' The Doctor folded away his grubby handkerchief. 'Have you noticed that this ledge is getting narrower at every step?'

Ian grinned bleakly to himself in the shadows.