The vehicle juddered to a halt just as Jasmine was starting to wonder if jumping on the back had been such a good idea after all. They were a good mile from the base now, and the brown sand was giving way to crumbling rock as they entered the shadow of a low ridge, forming the opposite rim of the great crater from the one on which the Tardis had landed. She quickly jumped down and dashed for cover amongst the stones as the vehicle's doors opened and Strole and his men, weighed down by their equipment, clambered out and made straight for a dark crack in the cliff face.

It was indistinguishable from any number of other fissures in the wall of stone which looked ready to collapse at any second under the monotonous pressure of the dust-filled wind, but all eight men vanished into it without trace. Jasmine gave them a couple of minutes to get well ahead and then, nerves flittering in her stomach, tiptoed cautiously into the blackness behind them.

Thankfully, she only had to feel her way along one narrow stone passageway in pitch dark before she turned a corner and there was light again, a soft bluish light issuing from the ruins of a thin metal door, set into the rock, which looked to have been smashed open with a sledgehammer. She crept through into a corridor built of some marble-like substance of such a perfect snowy white that it was hard to make out the join between wall and ceiling. Blessing the rubber soles of her new shoes, which pressed soundlessly against the metallic floor, she ignored a row of alternative openings and pressed on down the passage to peek around a doorway at the far end, from which Strole's booming voice was already clearly audible.

"Well now, Ceros, another session is upon us. Unless of course you're in a more cooperative frame of mind?"

The chamber was vast, built all of the same transluscent white substance and studded with thirty circular tables, each one six feet across and four feet high, illuminated by hazy beams of light projected from the ceiling far above. Jasmine stifled a gasp at the grotesque sight she saw squatting on each one. They were like green sacks of water, glistening wetly in the pools of black liquid filling the shallow round trays on which they sat seething. Yellow tendrils like the roots of unearthed plants wriggled and quivered in the air, and on each one a single great white eye swivelled in the direction of the eight intruders.

The rim of the table holding the creature Strole addressed pulsed with yellow light at each syllable as a gentle, harmonious voice, like that of an angel, filled the room.

"My answer must be the same, Max Strole. For the good of your own civilisation, we cannot give you the technology you seek. Nothing you do to us can change that."

"As you wish. Kerrigan."

Jasmine almost gave herself away, lurching forward to see, as a man with his back to her lifted his head from adjusting a bulky piece of equipment slung around his neck.

"Ready, Mr Strole."

His voice. She felt a heavy, sinking sensation as Kerrigan, his face hard and immobile as stone, advanced on the alien's table, the free end of a length of flexible cable, plugged at the other end into the contraption on his chest, held carefully up in front of him. She instinctively felt in no doubt as to what would follow.

"Please," came Ceros' beautiful voice. "I beg you..."

Jasmine clapped her hands over her ears and kept them pressed there with all her strength at the unearthly howl of agony that rang around the chamber and washed out into the corridor as Kerrigan touched the cable to the creature's soft flesh. Blue sparks crackled and spat from its shuddering body and its tendrils locked into broken, contorted shapes, on and on until the scream dried to a desperate, scraping croak and Kerrigan pulled the cable back. He held it there, ready for use, just inches away.

"You'll break in the end, you know," said Strole mildly, inspecting his fingernails. "Everyone does."

"Perhaps." The voice was as melodic as ever, but weak and quavering. "But I must try."

"Of course. But there's been a new development which might just make you look at things differently. You see, I've recently hired a man who understands all your gadgetry as well as you do. I might just be able to do without your help entirely."

"There are no humans who understand our technology. You are lying to us."

Strole gave Kerrigan a nod and Jasmine turned and buried her face in the wall as a second soul-rending shriek echoed around the room. A small mercy, this one ended after a couple of seconds.

"Actually I'm not lying," said Strole, continuing as if nothing had happened. "Not this time. So you might like to consider, perhaps it would be for the best if you just gave me the little bit of help I'm asking, so that I can go home and leave you all in peace to do whatever it is you do in here. Because otherwise, I'll find out anyway from my new scientist, and then I might as well as just have you killed." He stepped forward and placed his hands on the rim of the table, leaning forward to stare into Ceros' single eye. "All of you."

"My answer must..."

"Remain the same. I know." Strole motioned one of the guards forward. "Well, I'll leave you to sleep on it. But perhaps this will stimulate your thinking."

"NO!"

The pain in Ceros' voice was worse than the screams of the torture as in a flash of silver light from the guard's handgun one of the creatures exploded in a shower of green slime and fluid. Its trembling body seemed to deflate and decay before Jasmine's eyes, melting into an empty heap of blackened lifelessness.

"Think about it," said Strole, and with a curt gesture led his men out. Jasmine sank back into the nearest side corridor while they tramped past.

She rested there for a moment, leaning against the wall, eyes tightly shut, but when she felt the tears coming she shook her head and stood up straight. What now? Her gaze first followed the men on their way out, but they were just heading back to the base and it would be safer to walk rather than try to hitch another lift. Well then...

Softly, she made her way into the aliens' chamber. Ceros' eye fixed on her instantly.

"Welcome."

Jasmine blinked. This was a reaction she hadn't anticipated.

"I..." She pointed vaguely at the exit. "I'm not with them."

"I know," came the voice, like the ringing of bells. "I've been watching you. You sympathise with our plight. I appreciate it."

Suppressing an instinctive revulsion for the creature's vile appearance, which grew stronger as she approached, Jasmine cautiously drew nearer.

"I saw what they did to you," she managed. "Are you all right? Can I do anything?"

"Please don't distress yourself. I've suffered no permanent injury. Max Strole is very careful in that respect."

Jasmine halted just short of the table, still unable to stomach the idea of moving within arm's length.

"Why do you let them do this to you? You have all this technology. Surely there's something you can do?"

"I'm afraid not. My people are proud of their scientific achievements, but ultimately they led us down this evolutionary dead end, and left us physically helpless and dependent on machines for our very survival. Over time, the machines failed, or developed their own intelligence and abandoned us, and now we thirty... we twenty-nine I should now say... are all that is left of my race. Clinging to this last handful of life support devices before entropy claims them as well." The voice paused, and Ceros' eye swivelled mournfully downwards. "It is sad."

Jasmine looked around at the immobile green blobs occupying their featureless tables spread about the room, the dead one a black spot in their midst. A few of them moved their thin, useless tendrils feebly.

"Listen," she said. "I'm going to leave now, but I have a friend and I know he'll want to help when I tell him about you."

"Please don't endanger yourselves on our behalf. There is nothing that can be done."

"Don't worry," said Jasmine, backing towards the exit. "The Doctor always knows what to do."

Seconds later, she was at the cavemouth, and stepping out into the heat and dust of the outdoors.

"Halt!"

She froze, a cold hand clutching at her innards as she found herself penned in by armed men. Strole walked towards her, his face engorged with anger.

"Stupid girl. Did you think we wouldn't see your footprints? You should have kept your nose out."

"The Doctor will find out what you're doing in there," she fired back with spirit. "He'll never help you!"

"He'll help," said Strole. He grabbed the cable attached to the torture device around Kerrigan's neck. "He'll help when it's you on the other end of this wire."

Jasmine shivered and stared at Kerrigan as two guards seized her arms. The young man looked down at the dust, unable to meet her eyes.