The Doctor snorted rudely. 'You mean you couldn't get in.

That lock's a good deal more sophisticated than that old trionic lattice that Weng-Chiang's zygma cabinet used.'

HsienKo bowed graciously. 'Come. I will show you what I have achieved here, and why. Then we will be friends.' She smiled eagerly. Romana was more than a little curious, though showing it was beneath her, but fortunately the Doctor had no such qualms. His mouth twisted in that facial shrug of his and he strolled towards the cave, hand in pockets. He stopped suddenly. 'Where's Woo?'

'Safe. He has killed or injured a number of my troops, and I don't want anyone getting any misplaced desires for revenge.'

Her mouth quirked slightly.

'And K9?'

'K9?' HsienKo puzzlement was reflected as blatantly in her voice as in her expression.

'Yes, K9. He's about so high ' the Doctor bent to hold the palm of his hand about two feet off the ground ' silver, wags his tail and talks too much.'

HsienKo's expression cleared. 'That metal thing that was with you?'

'Exactly.'

HsienKo shrugged. 'I'm very sorry, I thought he was merely a child's toy. For riding on, yes?'

'A child's toy? You'd better not let him hear you say that.

Well, what are we all waiting around here for? Haven't you got some diabolical secret to show us?'

'Oh, that?' HsienKo smiled wryly. 'This way.' She led them into the cave mouth.

Romana caught up with the Doctor, leaning in close in the hope that HsienKo wouldn't hear her. 'What did she mean, Woo is safe?'

'Protective custody? He's probably in danger, but he can look after himself.'

'What about K9 then? We can't leave him stuck at the foot of the mountain.'

'I made a few improvements to Professor Marius' design.'

She had met the original at home on Gallifrey, where it had become quite a celebrity, but stairs were something it couldn't cope with. 'It'll take him hours, but he'll get here.'

HsienKo led them only a short distance into the peak, then brought them to a concrete wall containing a steel door. Two armed guards stepped aside to let her pa.s.s, and she held the door open for the Doctor and Romana.

The two Time Lords entered the room beyond curiously, and, in Romana's case, with some well-hidden trepidation.

'Welcome to our control room,' HsienKo announced proudly.

The Doctor and Romana looked down on the room below first. 'Heat exchanger and turbines,' the Doctor muttered. 'Put it together with radioactive materials on HsienKo's KMT junk and what do you get?'

'That?' Romana pointed across to the thicker gla.s.s opposite. They moved over to look through it. Romana traced the lines of the cables and suspended cylinders with her eyes.

'It looks like a primitive water-cooled fission reactor, judging by the layout. Surely this civilization can't be so advanced?'

The Doctor tilted his hand in a so-so gesture. 'The first reactor was built under a Chicago sports stadium in 1942.'

'Five years from now.'

'Yes.'

'But those cylinders do look like control rods or fuel rods.'

She looked at the Doctor sharply. 'Could they be trying to produce plutonium?'

'I don't see them getting weapons-grade material out of this set-up. Besides, why come to this precise location if that's all they were doing? They could have done that at HsienKo's house or the quarry. They wouldn't need those turbines for that either. No, they want the energy generated.'

'To boost the telluric current in the Dragon Paths?'

'Yes. They seem to be expecting Magnus Greel's return, and the only way to arrange that is to reach back through time and short out the zygma beam.'

'They can't do that with the output of one reactor. Perhaps if they could convert the energy into reverse tachyon chronons...'

'Greel wouldn't have been familiar with that idea, so I doubt that HsienKo could be. If they could alter the electrical frequency of the telluric currents to that of zero-point energy, they'd have a self-sustaining power source that's more than strong enough.'

'Zero point energy? The vibrational frequency of the universe? How could they do that?'

The Doctor looked around, a somewhat surprised expression on his face. 'I'm not sure.'

Woo stumbled as the mountain wrapped itself around his head, drawing him in. Lights flashed in front of his eyes and soon snapped up into the position light bulbs should normally hold in a human's viewpoint.

He, the sergeant and the two guards were standing in a guardroom like a million others in the world. A row of barred cages lined one side, while a few chairs surrounded a table and a small stove on the other. The sergeant removed Woo's Colts and dropped them on the table, while another guard went to open a cell. Woo wished he could be surprised. 'I take it my life expectancy has been substantially reduced?'

'Maybe, maybe not. HsienKo will decide later, but she doesn't like killing.' The sergeant snorted disparagingly.

'Only j.a.panese.' Oddly, this rea.s.sured Woo slightly. So long as they didn't know who he really was, he was probably safe.

'She wants to take Manchuria back for a start.' Woo was interested at once. Since the taking of Manchukuo had been the Sakura Kai's idea, they wouldn't be pleased to have it retaken by China.

The other guard opened the cell door. 'In you go.'

'Actually,' Woo said, with a look of supreme if feigned apology, 'I'd rather not.' He drew the katana katana from his back and swung it at the sergeant's head. Recalling what the Doctor had said about killing, however, he struck with the flat of the blade, stunning the sergeant, then rammed the hilt back into the jaw of the guard at the cell door. from his back and swung it at the sergeant's head. Recalling what the Doctor had said about killing, however, he struck with the flat of the blade, stunning the sergeant, then rammed the hilt back into the jaw of the guard at the cell door.

The last guard had unslung his rifle, but Woo slammed the katana katana into it before he could fire, and knocked the steel barrel up into the guard's face. There was a wet crack, and the guard toppled over, as unconscious as the others. Woo thought about that as he took his Colts from the table and slipped the into it before he could fire, and knocked the steel barrel up into the guard's face. There was a wet crack, and the guard toppled over, as unconscious as the others. Woo thought about that as he took his Colts from the table and slipped the katana katana back into its scabbard. This no-killing stuff did have an interesting challenge of its own, he had to admit. back into its scabbard. This no-killing stuff did have an interesting challenge of its own, he had to admit.

He slipped cautiously out of the guardhouse, which was on a landing a short distance below the red-brick gateway that stretched across the split peak. There was a very rectangular cave mouth on the next landing up, and Woo recalled that Romana had told himself and the Doctor that most of the important stuff was underground. Since he didn't know where the other entrances were, that was as good a place to start as any.

n.o.body was around as he ascended to the next landing, and he was grateful that it was August, three months after the pilgrimage season had closed. This business would be much harder with ten thousand pilgrims clogging the steps.

HsienKo had listened to the Doctor and Romana's conversation with interest. As she had suspected, their knowledge was far in excess of that of Weng-Chiang or herself. If they were to help her refine her discoveries, however, they would have to know more. 'You know what a tuned resonance circuit is, Doctor?'

'It's a very primitive method of energy transmission that works like a step-up transformer.'

'Primitive by the standards of yourself or Magnus Greel, perhaps, but the best we can do today. The principle is simple enough. High-frequency electrical pulses applied to a primary coil will produce ma.s.sively inflated pulses in a secondary coil.'

The Doctor ruffled his hair. 'Nikola Tesla developed the idea at the turn of the century. He thought he could tap zero-point energy by setting up a standing wave that would resonate at a suitably high frequency. His facility at Colorado Springs burnt out when he tried it.' He smiled apologetically.

HsienKo nodded. 'Tesla's own attempt to tap this energy failed because the generators of the local power company couldn't supply enough current. We don't have that problem. I have had this reactor built based on notes and doc.u.ments left by my father who took them from Weng-Chiang, or Magnus Greel, if you prefer. Those of us in this room all know he was no G.o.d. It will provide sufficient power to cause the secondary coil to resonate at the frequencies used by Greel's zygma beam. The zygma energy will be leached away from the beam through induction and re-broadcast across the Dragon Paths, with the magnetic field of the earth acting as a tertiary coil to further boost output.'

'And then?'

'Two things. One, the zygma beam will terminate here, and not in 1872. Second, the Dragon Paths will be far more powerful; strong enough to pierce the veil of Time.' She looked at him, willing him to understand what she was offering. 'Then, I can save this country, Doctor. The j.a.panese need never have invaded Manchuria. Millions of lives can be saved. You are known to have an abhorrence of war yes, I have tracked your exploits over the years so you must see how we can use the Dragon Paths to put right all those things.

And then Kwok and I...We shall explore; see what life offered us in the greatest eras.' She thought about it warmly. I shall run with dinosaurs, and breathe the air not yet tainted by man.

'We might just decide to be Adam and Eve.' She was only half serious.

The Doctor shook his head wearily. 'I thought you had been thinking along those lines. You'll never do it. Don't you see? Tesla's set-up was seventy-five feet in diameter and two hundred feet high. To generate the sort of power you're talking about and transmit it into the Dragon Path network, your generator coils would have to be...' He trailed off, as if unable to think of a suitably impressive word.

'Mountainous?'

'Well yes, that's a good desc' The Doctor's face fell. 'Ah.

Mountainous?' HsienKo nodded. 'The piezoelectric properties of the rock?'

'Very good, Doctor. My father's earnings and contacts and my own extended life-span have allowed me to gain the best education available. Even now, it isn't yet complete, for all of one's life is a learning experience. However, I have learnt of the conductive properties of the crystalline deposits found in certain rock formations, such as we have here. The crystals in these rocks will carry an electric current as efficiently as copper wiring if you can stimulate them properly, and we can.'

'And then you won't get the safe exploration and humanitarian exploits you want. You'll get the nasty truth of the Blinovitch Limitation Effect, which says you can't change history. HsienKo, don't you see what will happen if the zygma beam terminates here? You would never have been irradiated with chronons while in the womb. You would never have come to rule the Black Scorpion, or built all this.'

'That's what they said about Greel! They said man couldn't travel through time in the zygma beam, but he did. You can't trick me, Doctor.'

'You're already tricking yourself. Greel was a scientific incompetent who got lucky; you can't trust that precedent. The paradox would produce a temporal embolism centred on you, and the world would be stuck in an alternate timeline with Weng-Chiang to rule it.' The Doctor's voice was thick with disgust.

'Let Weng-Chiang rule?' HsienKo laughed. 'No, no, Doctor; how long would it be before it was my turn for his death machine?' The laughter drained from her face, leaving a grim mask of hatred as she leant closer. 'He dishonoured my father, then abandoned him to die.'

'You must have loved him very much to go to these lengths to avenge him.'

HsienKo's hesitance masked the hatred. 'I hardly knew him. Weng-Chiang dragged him off on his wild-goose chase around the world soon after I was born. He used to write often, though, until I was sixteen. Then the letters stopped. Weng-Chiang stole my father from me, enslaved him and discarded him like table sc.r.a.ps. I'm not going to let the little matter of his being dead stop me from avenging my father.'

She straightened. 'I have the blueprints for his organic distillation cabinet and have modified the design slightly, thanks to the very comprehensive notes left to me by my father. It will absorb the life energy of any being down to the smallest mammal. Oh, it will keep Magnus Greel alive barely fed by the occasional rat or vole; no more than that.'

She smiled icily, her eyes focusing on some slightly distant point. 'And he will live as I wish him to: trapped for all eternity in the prison of a body held constantly at the moment of death. Immortal, and in perpetual agony as his tortured flesh twists and writhes on the bones.' Her breathing became more shallow and she fell silent for a moment. 'If I so desire, and if it amuses me, I could inflict any torture upon him that the human mind can conceive and keep him alive to savour every moment, no matter how much damage is wrought upon his body.'

'You must be very proud,' the Doctor muttered darkly.

She snapped back a calm demeanour. 'No, I'm not. I hate what I've become because of Greel. Surely you of all people understand that Greel must be formally punished. Isn't that what you yourself would have wanted?'

'Greel paid the price for his lack of responsibility. Cellular collapse isn't a very pleasant fate.'

'It's not good enough!' HsienKo slammed her fist onto the tabletop to punctuate her opinion. 'Dead he is but a martyr to the sheep who followed him. Most of these fools still believe he was a G.o.d, granted divine providence to rule, with them as his chosen ones. Look at me: young and beautiful? So people tell me; it's a gift from Weng-Chiang, according to the believers.' Her eyes moistened as she continued in a snarl.

'Sterile and with a future of watching everyone I love age and die? Is that a gift? Doesn't Magnus Greel deserve to be shown for the twisted and debased creature he was, instead of revered as a sadly missed leader?'

'Greel was convinced of his own justifications for ma.s.s murder and scientific lunacy, and you're doing exactly the same thing. If you short out the zygma beam, you will alter everything that your life has touched in any way.'

HsienKo went white with anger. To compare her to the vile creature who had inflicted such pain on her was beyond forgiveness. 'No! You should understand. You know what Greel was; you should be standing with us!' Why was the Doctor taking this att.i.tude? It was he who caused Greel's death, after all.

'Understand? I understand all right. I understand that single-minded obsession is one of the human species' most dangerous traits. You've murdered, stolen and perverted the laws of nature just to satisfy the obsession of redeeming your own self-pity; how can you ask me to cooperate with that, eh?

Even without the anachronistic knowledge pa.s.sed on by your father, you have one of the finest intellects in the world in this era, and you squander it on a "misplaced desire for revenge".'

HsienKo was stunned into silence. After all the reforms she had made in the Black Scorpion and the friendship she had offered the Doctor and Romana, he had the gall to accuse her like this. Did he not see how she had to do this to honour her father? Probably not; he was just a barbarian gwai lo gwai lo after all. after all.

'Out!' she screamed. The guards looked at each other. 'Get these two out of my sight!'

'Where to?' one guard asked nervously.

'Just take them to the guardroom cells. I'll think of a fate for them later.' If Sin doesn't get them first, she thought. She turned to Ying, who flinched at her expression. 'Has the reaction continued to be stable?'

'Yes. Multiplication factor remains one precisely. Power output now fifteen thousand kilowatts.'

The news calmed her, though she could still feel the veins throbbing in her head. The Doctor would see things her way eventually. First, though, she must go through with it. 'Switch power through to the primary coil.' Ying nodded, and turned to the instrument banks to redirect the current generated by the reactor through the cables that webbed the caves and into the crystalline structure of the rock itself.

Sin was no longer in the caverns. He had moved towards an area which had a slightly greater warmth. Both his strategy subprocessors and his swinish instincts suggested that any humans in the vicinity would be attracted to the heat even if they weren't the cause of it.

A cooling body lay a short distance from a stone ramp; Sin reached out a hand to gently stroke the cold flesh. He pressed harder with his moulded fingers, not feeling the skin split and tear, but seeing the white-painted fingers sink more deeply in.

His fingers come out red and glistening, but the blood did not flow in the way that it did when fleeing a living body and taking life with it. This human had been stolen from him, but its presence was an appetizer, teasing his desires.

Flicking the cold blood off his fingers, Sin marched up the ramp and turned a corner to find two live humans waiting for him. Their heat-traces shifted discreetly as they saw him and they moved on the spot, trying to bring weapons to bear on him. Sin lunged at the nearest, lashing out with eager delight.

A spray of light, quickly cooling to dark droplets, erupted from the human as Sin's knife opened an artery.

The human started to fall, his heat pattern blurring with rapid changes, and Sin impaled the central bright spot. The human stopped struggling, but his companion was able to fire his weapon. The projectile hit Sin in the back, pushing him face-first into the darkening centre-ma.s.s of his first victim.

Sin turned with inhuman speed, knocking aside the second guard's gun before it could fire again, and swinging the knife into the human's arm. Misty light sprayed across the human as Sin opened the inside of his arm from elbow to wrist. A backhanded tear sent more tendrils of warm light stretching for the floor.

Sin shook himself free of the clinging pieces of flesh and turned to the door. He started looking for an opening mechanism.

Li was considering what he could do with the controls to sabotage the Tong's plans, but the arrays of gauges, dials and switches on the boards attached to the mechanisms here were beyond anything he had seen before. They all measured temperature or pressure, and in the case of the turbines speed, but which controls would affect which mechanisms in which ways was a total mystery.

'You,' someone called. Li ignored it, a.s.suming the man was calling to someone else. A hand spun him round. 'You!