Pinned by the bright beam of light the figure was revealed as a metal man, scorched and battle-scarred. It had an accordion-like control unit on its chest and strange jug-like handles projecting from the sides of its head. Its blank metal face comprised black circles for eyes and a slit for a mouth. Its left arm was a clockwork lash-up of cogs and levers. From the right side of its mangled chest spilled a ma.s.s of plastic tubing and exposed circuitry.

Jo blanched. 'Oh, heck.'

'A Cyberman,' breathed the Doctor Jo's instinct was to turn and run back into the TARDIS, but she kept her torch beam trained on the huge creature. 'Where's it come from?'

'At a guess I'd say it's a casualty of their last invasion. It must have been injured and taken refuge in the sewers. It's been rebuilding itself ever since from whatever bits of machinery it can salvage and cannibalise.'

'Did it build the rats, too?'

The Doctor nodded. 'To bring it machine parts and spread the Cyber-infection. Even damaged, the Cybermen are single-minded, resourceful and highly dangerous.'

Since rising to its feet, the Cyberman had not moved. It seemed to be acclimatising itself. Suddenly it emitted a metallic rattle.

'What's it doing?' hissed Jo.

'Trying to speak. But its voice box must be damaged.' The Doctor raised his hands placatingly and flashed Jo a smile, though she could see he was worried. In a soothing voice he said, 'Don't worry, old chap, we won't hurt you.'

At once the Cyberman lunged forward, crashing through the heap of components. It raised its arms, metal hands grasping, and made a beeline for Jo. She stumbled back, torchlight jerking erratically over the creature's metallic surface. The Doctor rushed forward to try to stop it, but it swept him aside with ease.

Still tottering backwards, the heel of Jo's boot came down on a chunk of metal and she fell. Dropping the torch, she landed with enough impact to jolt the breath from her body. The Cyberman loomed over her, its fingers creaking open as it reached towards her face. Jo opened her mouth, trying to scream...

But then the Cyberman stopped moving.

For a moment it resembled a clockwork toy whose winder had run down. Jo blinked as a matrix of crackling blue electricity began to dance and spark around its head. Then came a m.u.f.fled bang from inside its blank-faced helmet and black smoke began to pour from its slit of a mouth.

Like a downed statue, the huge figure toppled towards her. Jo thought she was about to be crushed, but then hands grabbed her and yanked her out from under the falling Cyberman. As it crashed to the floor, she sobbed with relief and clung to the Doctor.

'What... happened?' she gasped.

The Doctor indicated the metal rat he had taken from his pocket. It was crouched on the floor close by, its eyes blinking red.

'The Cyberman's brain was malfunctioning, which meant its defences were down. Before coming here, I modified this little fellow to transmit a signal to short out the Cyber implants in our friend's head.'

'You knew he'd be here?' said Jo, looking at the Cyberman.

'Educated guess,' the Doctor said. Producing his sonic screwdriver, he added almost sadly, 'Time to finish the job.'

He turned the screwdriver on and applied it to the edge of the Cyberman's faceplate. As the plate came loose and the Doctor prised it off, Jo caught a glimpse of what remained of the once-human face beneath. She turned away, feeling sick, and tried to concentrate on remaining as professional, and as scientifically detached, as the Doctor.

'What are you going to do?'

'That poor chap at the hospital was impregnated with living technology Cyber technology. If I know the Cybermen, they'll be using him to create potential new recruits as we speak. But if I can transmit the right signal from our friend's brain I can not only lure all the Cyber rats back here, I can also draw out the Cyber technology from whoever it's infected and neutralise it.'

'Kind of like the Pied Piper and his pipe,' Jo said brightly.

The Doctor smiled. 'Kind of.'

Sergeant Benton knew the situation was hopeless, but there was no way he would ever give up it simply wasn't in his nature. He would keep fighting until he could fight no longer even if, in this instance, 'fighting' meant 'running away', or more specifically trying to keep one step ahead of the remorseless tide of silver worms, which were sweeping through the hospital, converting patients and medical staff alike into robotic zombies.

Together with a rag-tag group of survivors he had picked up en route a Scottish porter called Don, a young woman called Mary who had been visiting her sister, a traumatised young boy who had seen both his parents engulfed by silver worms, and a dark-haired nurse called Holly who was still clutching the plastic bag of blood samples she had been transporting from one part of the hospital to another Benton was fighting a desperate rearguard action. Evacuating and locking down the hospital, as per the Brigadier's orders, had proved an impossible task, such was the speed at which the worms had infiltrated the building's many floors and corridors. Even getting his own little group to safety had so far been beyond him. Each time they headed for an exit, they found their route blocked, either by yet another flowing wave of worms or by the lurching approach of converted humans, their skin glittering with circuitry.

In the past half-hour, Benton and the rest of his group had seen dozens of people converted. It was a horrific process, the worms flowing up and over the bodies of their victims like a slick of living metal, finding ingress through nostrils, mouths, ears, even the pores of the skin itself. The worms made no distinction between the young and the old, the healthy and the infirm. If it was living, breathing flesh it was all fair game to them.

It seemed that there was no way of stopping the worms' relentless progress, no way of stemming the flow. As far as conventional weaponry was concerned, it was the same old story. Bullets were useless against the worms, whereas opening fire on the converted humans was, of course, entirely out of the question. Puppets of an (he a.s.sumed) alien intelligence they may be, but they were still people, and therefore hopefully not yet irredeemable.

Benton's group were now on the hospital's fourth floor, having fled up a flight of stairs from the floor below with a horde of converted humans in hot pursuit. The sergeant was concerned not only by the fact that his party was being forced gradually upwards as each potential avenue of escape was denied them, but also by how much longer certain of them could keep going. Don the porter, who must have been nudging 60, was sweating and wheezing with exertion, and even Benton himself was hampered by having to carry the little boy, who was trembling like a frightened kitten, his face buried in the sergeant's chest.

'This way!' Benton shouted, leading the group at random along an unoccupied corridor. He rounded one corner, then another, alert for an exit that might, by some miracle, lead them down through an as-yet worm-free part of the hospital to safety.

His heart leaped with hope as the five of them rounded yet another corner and found themselves flanked by two double sets of lift doors. Just beyond the lifts was another door this one glazed with reinforced gla.s.s, above which a sign read STAIRS.

Murmuring a silent prayer, Benton hurried across to the door and tugged it open. He listened for a moment. Silence.

'Is it safe?' asked the nurse, Holly, who was standing behind him, trying to peer over his shoulder.

Benton, the little boy still clinging to his chest, shrugged. 'I can't guarantee it, miss, but I think it's our best bet.'

They started down, Benton moving cautiously, the rest of the group trailing him like shadows. As they reached the door leading out on to Floor 3, he allowed himself to believe that maybe, just maybe, they might make it out in one piece, after all.

They were halfway down the next flight when Benton suddenly halted.

'What is it?' hissed Holly.

He put a finger to his lips. 'Listen.'

They all froze. From somewhere below them came a rustling sound, like the stealthy march of fire through dry gra.s.s.

'I think we should go back,' said Benton.

'What do you-' began the young woman, Mary. But then they all saw what was making the sound, and the words dried in her throat.

Worms. Thousands of them. They suddenly appeared at the bottom of the stairs that the group had been descending and began to flow towards them like rising floodwater.

'Back!' yelled Benton. 'Everybody back!'

But no sooner had the words left his mouth than the door to Floor 3 above them crashed open and more worms spilled through, accompanied by a lurching mob of converted humans.

Benton looked wildly up and down, but there was nowhere to go; they were trapped!

He clutched the little boy to him as Holly screamed and Mary whimpered and curled into a ball, her hands over her head. Benton closed his eyes, wondering what it would feel like to be converted, whether it would be painful.

He was doing his best to prepare himself for the experience when everything stopped.

For a moment he wondered whether this was part of the process, whether the conversion was already taking place, and that the first things to be subsumed were the subject's senses.

Certainly he could no longer hear anything. The metallic rustling of the worms had stopped, as had the lumbering advance of the converts.

Tentatively he opened an eye.

He was surprised to see that the carpet of worms that had been flowing up the stairs were now motionless, as were the ma.s.s of worms that had been descending towards them from above. And the converted humans now resembled deactivated robots. Their heads had drooped forward and their hands hung loose by their sides.

He waited, tense, expecting the worms to start moving again at any moment.

But when they did, it was in an unexpected direction. To Benton's astonishment, the worms suddenly turned in a rippling wave and began to retreat, to head back in the direction from which they had come. And what was even more astonishing was that those worms that were controlling the human converts began to follow the lead of the general ma.s.s, pouring from the mouths, noses, ears and even from underneath the fingernails of their victims, and joining the unexplained and seemingly miraculous exodus.

The convert that was closest to Benton, a bearded man in a blue hospital gown, dropped to his knees. Benton watched as the threads of alien circuitry retreated and eventually disappeared from his skin and the silvery sheen faded from his eyes.

The man blinked, coughed, took a deep breath, then fixed his bewildered gaze on Benton.

'What am I doing here?' he asked in a croaky voice. 'What's going on?'

Benton couldn't help but grin at him. 'Your guess is as good as mine, mate,' he said.

Twenty-four hours later, the mopping up operation was complete. UNIT troops had cleared the dead Cyberman and the inert Cyber rats from the sewers, and all those infected by Cyber worms in the hospital had made a full recovery.

When Jo walked into the UNIT laboratory, however, she found that another battle was raging. Good friends though they were, the Doctor and Brigadier were at loggerheads and not for the first time.

'Research facility!' the Doctor roared. 'Are you insane, man?'

The Brigadier's response was equally acerbic. 'I a.s.sure you, Doctor, that all alien materials are handled with the utmost respect and delicacy. Furthermore, the security measures-'

'Security!' scoffed the Doctor. 'The Earth won't be secure until that technology has been utterly destroyed.'

'What's going on?' Jo interrupted.

The Doctor glared at her. 'This dunderheaded species of yours, Jo, appears intent on breaking open Pandora's Box.'

Jo raised her eyebrows at the Brigadier, who frowned.

'The Doctor is opposed to the government policy to transfer all recovered alien technology to a secure research facility, where it can be studied under laboratory conditions. Technology that could be of great benefit to mankind. For example, Dr Raith says we could use all these Cyber-doodads to help the sick and the dying...'

Jo had to admit it sounded reasonable. She turned to the Doctor. 'Perhaps he's right?'

'Of course he's not right!' snapped the Doctor. 'Mark my words, Brigadier, Cyber technology is a plague and one day it will infect you all.'

But it was clear the Brigadier refused to be swayed. The Doctor turned to Jo for moral support, but saw that she couldn't understand his anger either.

Grabbing his cloak he swept from the room. As he strode away his voice echoed back along the corridor.

'When it does, just don't expect me to be there to pick up the pieces.'

A door slammed. There was a moment's silence.

'He will be, though, won't he?' Jo said finally.

The Brigadier sighed. 'I hope so, Miss Grant. I truly do.'

'It's an inhibitor. It's not activated. I need you to switch it on.'

'What does it inhibit?'

'Emotion. It deletes emotions.

Please. I don't want to feel like this.'

Danny Pink and Clara Oswald, Death in Heaven (2014)

We talked in Chapter 2 about the many problems s.p.a.ce presents to the human body, such as weightlessness weakening our bones and tissues. That presents major challenges if we are to send people to live on the Moon or Mars, let alone further out into the universe. But in 1960 two scientists proposed a radical solution.

In an article published in Astronautics magazine, American neuroscientist Manfred E. Clynes and psychiatrist Nathan S. Kline suggested that instead of going to all the trouble of building Earth-like environments in s.p.a.ce for astronauts to live in, it was more logical to alter astronauts' bodies to suit the conditions of s.p.a.ce. Just as, they said, 'in the past evolution brought about the altering of bodily functions to suit different environments,' (as we saw in Chapter 11), we might now make biomedical, physiological and electronic modifications to the human body. In effect, we could use science to evolve our bodies artificially.

This wasn't an entirely new concept. Science fiction writers had already explored the idea of mechanically adapting people to the conditions of s.p.a.ce, such as American author Cordwainer Smith in his short story 'Scanners Live in Vain', first published in 1950. But these stories generally explored the disturbing psychological effects of such a transformation, whereas Clynes and Kline spoke about their proposed modifications as a kind of liberation. They argued that a person in s.p.a.ce would no longer need to be 'a slave to the machine', having constantly to check and adjust systems to be sure of staying alive. Instead, an automatically 'self-regulating man-machine system' would mean the modified human was 'free to explore, to create, to think, and to feel' in s.p.a.ce. Creating such a man-machine would, they enthused, 'not only mark a significant step forward in man's scientific progress, but may well provide a new and larger dimension for man's spirit as well'.

We can see the lasting influence of Clynes and Kline's article in the word they invented to describe their s.p.a.ce-travelling man-machine. Since the 1940s, studies of control systems and effective action in animals and machines had been labelled 'cybernetics', from a Greek word for governor or pilot. Clynes and Kline called their man-machine a 'cybernetic organism' or 'cyborg'.

It has been argued that cyborgs already existed in real life before we had a word for them. Some people say that a person driving a car (or another machine) can be a cyborg because the controls and responses become such second nature an extension of the body that in effect it becomes a single unit.

It's also been argued that the word cyborg wasn't widely used until it featured in a book by American journalist David Rorvik, As Man Becomes Machine (1971). Certainly, the term didn't appear in Doctor Who until Terror of the Zygons (1975). But by then, the makers of Doctor Who had already created one of the series' most successful monsters, a race of self-regulating man-machines called Cybermen first seen in The Tenth Planet (1966).

In fact, there are two important differences between the Cybermen in Doctor Who and the man-machine cyborgs proposed by Clynes and Kline. Cyborgs were a solution to the problem of sending people into s.p.a.ce, but s.p.a.ce exploration was not the reason that people from the planet Mondas turned themselves into Cybermen. We're told in The Tenth Planet that they were getting weak, their life spans getting shorter. As a result, cybernetic scientists devised 'spare parts' to patch up the failing human bodies until they could be almost entirely replaced by machine components.