He looked back at the young man. 'Look, I'll be frank. I'm not in a position to offer guarantees, but I do have some influence within the UN on account of my previous services. I could try to obtain a new hearing for your people - '

But the older Arab was shaking his head sadly. 'Listen,' he said in Arabic. 'If your friend is in that place, he is gone. He is dead - worse than dead. He is one of the dancers. If you see him again, it will be your time to die. Believe me: it is better that we all leave, and warn the world.'

The Brigadier shook his head. 'The Doctor always manages to survive when you'd least expect him to. I think we should - '

He was interrupted by a shout in Arabic. ' Sakir! Sakir! There is a helicopter!' There is a helicopter!'

He looked round, saw someone pointing to the north, at the same time heard the faint sound of rotor blades.

'We have to take cover,' said the Brigadier, taking charge of the situation automatically. 'The chances are that those are alien aircraft, not helicopters at all.'

Tahir was staring at him. 'Are you mad?'

'It's not impossible,' said the Sakir Sakir. 'And anyway it doesn't make any difference. They are hardly likely to be friends of ours.' He started shouting instructions. Men with guns dived for cover. Others hurried towards the protective shadow of a ravine.

'Good strategy,' commented the Brigadier - but both the Sakir Sakir and Tahir had gone, running across the encampment towards the ravine. and Tahir had gone, running across the encampment towards the ravine.

After a moment's hesitation, the Brigadier set off after them.

Behind him, the sound of the turning blades grew closer.

It was Akram who saw the gun first. He grabbed Jo's arm, pointed.

Jo saw a machine-pistol lying half under one of the honey-globes.

Akram whispered something in French which Jo didn't follow, and before she could question him began to slither down the slope.

Jo hesitated, then followed, but when she reached the bottom Akram had vanished. She stayed behind the first of the honey-globes, tried to get a look at the thing that was carrying the Doctor. She caught a glimpse of grey, shiny skin, with the Doctor's booted foot flapping against it. Before she could react, there was a burst of gunfire. Jo jumped forward, saw the Doctor's body sliding down the side of the creature.

He hit the ground, flopped like a rag doll, landing on his back almost at Jo's feet. She crouched down, brushed the loose frost from the Doctor's face and put her hand an inch above his mouth. A slight movement of cold air told her that he was breathing.

'Doctor!' she said. 'Doctor, wake up!'

Another burst of gunfire rattled from somewhere in the chamber; Jo heard Akram's voice shouting, 'I am almost out of bullets!

Quickly!'

Jo shook the Doctor violently. 'Wake up, Doctor! Please!'

The Doctor's eyes opened. 'Jo? What are you doing here?'

His voice was weak. With a frown, he dusted the remaining melting ice away from his face, then gingerly explored his ribcage with one hand.

'Not too bad,' he muttered, sitting up slowly.

Suddenly, Akram screamed.

'I've got to help him,' said Jo, springing up. She started to move away, but the Doctor reached out and put a restraining hand on her arm.

'It's too late for that, Jo,' he said solemnly.

Jo heard the sound of bones splintering, followed by a horrible, agonized gurgle that faded into silence. She felt the blood drain from her face. She stared in the direction of the sound.

'If I hadn't asked him to help - '

'I know,' said the Doctor quietly. 'Come on, or we might be next.'

He stood up, keeping his head down to avoid banging it on the low roof, then started to run along the row of honey-globes. His hand was still gripping Jo's arm: she didn't have much choice but to follow.

She looked over her shoulder, thought she saw the bottom of the slope where she and Akram had descended from the mushroom forest. 'Doctor, we're going the wrong way. Akram and I came from - '

'Yes, Jo, I know,' interrupted the Doctor. 'But we can't just run away. We have to find out - '

He was interrupted by a hollow booming noise, rather like a muted drum-roll. It went on and on, echoing from the walls of the chamber.

Jo tried to cover her ears, but it didn't seem to make much difference.

'What is it?' she shouted.

'Alarm call, I should think,' said the Doctor. 'Don't worry, if I'm right this should be the main ventway.'

He gestured ahead. Jo saw a high-roofed tunnel leading down into darkness. 'But where does it go, Doctor?'

The Doctor turned to her and grinned. 'That's what we've got to find out.'

The Brigadier put his eye to the binoculars and watched as the gleaming spot with the fluttering rotor blades moved into the centre field. Still out of anti-aircraft range, he thought; but a clatter of gunfire along the gully told him that not everyone agreed.

The sh.e.l.ls burst harmlessly, well short of the target. The thing carried on approaching, and suddenly the Brigadier realized that it wasn't one of the alien objects he'd seen last night. It was a perfectly normal human-made helicopter - In fact, a very familiar helicopter - In fact, his his helicopter. He could even see the UNIT acronym emblazoned in large, friendly letters on the side. helicopter. He could even see the UNIT acronym emblazoned in large, friendly letters on the side.

'Yates!' he shouted. 'What the h.e.l.l are you doing?'

He looked around for someone who might be able to give orders, but there was only an Arab boy with a light machine-gun, who was staring at the Brigadier as if he were mad.

How had Yates got out? thought the Brigadier, then decided it didn't matter. What mattered was that the Captain was up there in the UNIT helicopter and the Gilteans were about to shoot him out of the sky. He stood up, shouted down the length of the gully.

'That's my helicopter up there!' yelled the Brigadier. 'Cease fire!'

The Arab boy next to him continued to stare, and there was a rattle of light machine-gun fire from further down the path. The Brigadier set off at a run to the place where the Sakir and his son were stationed, his shoes slipping on the loose gravel.

It occurred to him that Yates had no way of knowing he was with the Gilteans. He would have flown to the last known position of the Superhawk; having seen the parachute canopies on the ground he'd have known they were in the area and now he was having a scout around to see if he could find them. But now that he'd been fired on, he would probably withdraw.

The Brigadier saw Tahir crouching in the shadows, cradling a machine-pistol.

There was another burst of gunfire from along the gully: fortunately, it all fell short. The Brigadier looked over his shoulder.

'For G.o.d's sake stop that!' The chopper had lurched upwards when the sh.e.l.ls exploded. Now it was hovering at about a thousand feet.

The sound of its engines echoed around the slopes, mixed with the fading rumble of the sh.e.l.l bursts.

The Brigadier heard the Sakir Sakir's voice shouting something; he hoped it was an order for a cease-fire. He ran up out of the gully into the sun. He could still see the helicopter, but it was clearly moving away. He jumped up and down, waved his arms.

After a moment, the chopper began to swing around, circling the site but keeping a safe distance. The Brigadier imagined Yates or perhaps Benton trying to focus a pair of binoculars on him. He carried on waving his arms as the chopper completed two wide circles. At the end of the second, it came in, slowly, and high - for a quick get-away in case of trouble, no doubt.

He heard footsteps behind him, turned and saw Tahir Al-Naemi.

'You are leaving us, Brigadier?'

The Brigadier looked at the incoming helicopter again. 'I hope so.'

The Arab extended a hand. 'Good luck. I am sorry that my father shot you.'

The Brigadier shook, left-handed. 'So am I! - But it was an understandable mistake,' he added politely.

The helicopter was quite close now: the Brigadier turned and beckoned it in, pointing at a patch of level rock just beyond the parked jeeps.

'I hope you will tell them we are disciplined soldiers, not terrorists,'

shouted Tahir suddenly over the growing racket of the engine.

The Brigadier frowned at him, then nodded. 'I'll try,' he said. 'But I can't guarantee that they'll listen.'

Tahir nodded, then ducked back down into the gully as the Brigadier ran towards the descending chopper. From the corner of his eye, the Brigadier noticed that the guns were still trained on the craft.

'Well, I hope you are disciplined soldiers,' he muttered to himself.

He didn't want to think about what was likely to happen if any of them weren't.

The chamber was bigger than any that Jo had yet seen: ahead, stumpy pillars of rock receded into the distance until they merged together into a dimly glowing mist. Huge, translucent eggs hung from the pillars and the walls, bunched like grapes, or sometimes in larger ma.s.ses, like frogsp.a.w.n. The nearer ones had distinct shadows inside them, shadows that looked disturbingly human.

She stopped, stared. 'Doctor - '

The Doctor looked over his shoulder. 'Come on, Jo. There's no time to lose.'

As if she'd needed a further reminder, chitinous rattling sounds became audible from the tunnel behind her. She jumped forward, grabbed the Doctor's hand. He strode on, leading the way through the maze of pillars as if he had a map of them. As they walked, the ground grew softer - not squelchy, but peaty and dark, like potting compost - and the air grew even more humid. Thin, waist-high plants with dark purple leaves sprouted in the clear s.p.a.ces between the eggs; some of them were infested with a bluish fungus.

'Be careful not to go too near the eggs, Jo,' said the Doctor suddenly. 'They're quite close to hatching.'

Jo, who had in fact been avoiding the eggs as far as possible, glanced across at the nearest heap and saw that their skins were shrivelled and puckered, the human forms inside them quite clearly defined. She shuddered.

'Are they going to hatch into people?' she asked.

'Well, not exactly. Quasi-people would be a more accurate term, I should think.'

There was a movement somewhere ahead. A leg - an arm - a body came into view, dressed in combat fatigues. Slime trailed around it as it shuffled towards them. Blank eyes stared.

Jo took a breath as the Doctor steered her away.

'Doctor,' she whispered. 'That's one of Vincent's men. He was in the hospital. His name is - was - ' She tried to remember.

'Don't say his name,' murmured the Doctor. 'He may recognize it.

We don't want him following us.' He led her towards a darkened s.p.a.ce between the pillars, thick with the purple vegetation.

'You mean -' said Jo, as they pushed their way between the leaves '- they can remember who they were?'

'Up to a point, I should think. There wouldn't be much point in making the copies otherwise.'

Jo shuddered again. 'But what are the copies for?'

'I wish I knew, Jo,' said the Doctor. 'To go to such lengths to produce humans in bulk when they already have fighters of their own doesn't make much sense.' He stopped for a moment, broke a leaf off one of the plants and examined it thoughtfully. Jo saw a small pod, like a b.u.t.terfly chrysalis, hanging from the tip of the leaf. 'Unless of course that's only the first stage.'

'First stage of what, Doctor?'

But the Doctor didn't reply, merely set off again, but in a different direction. Jo glanced around her, shrugged, and followed him.

The vegetation had become quite dense. The thick stems of the plants pushed against her, and the leaves shed cold water on to her clothes. She saw smears of something dark on her arm, hoped it wasn't a parasitic fungus like the one that had infested her on Spiridon.