It was the first time someone had spoken since they’d scaled the sheer drop into the valley. The blip on the GPS terminal was telling them to go further into the geyser field. Doherty led the way, navigating around the more obvious vents. Where plumes of superheated gas erupted at noticeably regular intervals, there looked to be mini volcanoes, like termite hills where the metal torn apart by the force of the geysers had settled around the vent-holes. Those they could avoid.

But every now and then a geyser erupted without warning. Sometimes there was no volcano, no termite hill, because the geyser was weak. They shot a few feet into the air with a pop, then disappeared a moment later. It wouldn’t have been enough to knock a man off his feet, but the gas was so hot it could have burnt the flesh off his leg in under a second. The Doctor kept to the back of the group.

Even more dangerous, however, were the new geysers, the ones where pressure had been building underground, beneath all the metal scrap, and suddenly exploded upward. The eight of them saw one such geyser erupt a mere hundred feet away. They felt the earth tremor preceding it, and the heat blast that swept over them was enough to make the Doctor close his eyes and shield his face.

Sergeant Cameron stopped and looked back. They seemed to have been walking for a long time, but it didn’t seem like they had got very far.

“Doctor, are you sure about this?” He waited for the enigmatic man in the leather jacket to catch up. “This has got all the hallmarks of a nasty trap.”

The Doctor shook his head as a geyser burst to his right. “Did the Cybermen look very worried about your presence here, Sergeant? They don’t think in terms of defence strategies. If they’ve built their base here, in such a precarious location as the middle of a geyser field, then there must be a good reason for it.”

“You seem to know a lot about them,” Cameron began, but a powerful geyser erupted in the distance, and the Doctor didn’t hear him.

“You seem to know a lot about them, Doctor,” he repeated.

The Doctor sighed. “Comes from experience, I’m afraid.”

“Well, I’m glad someone lived to tell the tale.”

The Doctor lifted an eyebrow and Cameron gave him a wry smile.

“A tale I’d very much like to hear,” he added.

“I don’t know if we have time.”

“Why? How long is it?”

The Doctor sighed again. “Well, that depends if I start at the beginning. Have you heard of a planet called Mondas, Sergeant Cameron?”

The Doctor found the story was on the tip of his tongue. Names, faces, places and dates came rolling out of memories he didn’t even know he still had.

He told Sergeant Cameron about the planet Mondas, the tenth planet in Earth’s solar system, and pretty much its identical twin. Aeons before the ancestors of bipeds even flopped out of the seas on either planet, Mondas broke away from its orbit of the sun and ended up drifting through space for millions of years before its course took it back through Earth’s solar system. By that time, mankind was not only the dominant species on Earth, but he had begun his conquest of space.

Humanity had evolved on the planet of Mondas even earlier and its people were technologically ahead of Earth millennia before the planets crossed interstellar paths again. But in a cruel twist of fate’s knife, the development of the two planets diverged even further when a plague arrived on Mondas from outer space. The plague ravaged mankind, decimating society and bringing the people of Mondas close to extinction. Were it not for their technological advancement, they would all have died out when their brothers and sisters on Earth were still enamoured with gods.

At first, technology offered a cure. Those who found themselves struck down by the plague could sacrifice their infected limb or organ and have them replaced with a serviceable mechanical substitute. But it was a piecemeal process. Once one part of them was sacrificed, it didn’t mean the rest of them was immune to the plague. Bit by bit, the people of Mondas began to willingly embrace cybernetic conversion for limbs and organs that weren’t even infected. The bacterial agent could only destroy living tissue, so in machinery, there was immunity; in machinery, survival.

And the people of Mondas did survive. By the time the people of Earth were grappling with their own Black Death, the people of Mondas had rid their world of the plague that had almost threatened to wipe them out a millennium previously. They had been routinely grafting cybernetic enhancements onto their persons for so long that it was no longer a questioned practice. Even when they gave up their hearts to a more efficient, longer lasting electronic pump, they still saw themselves as human; even when they chose to have half their brains removed and the other half wired into a more effective processing unit, they still saw themselves as human.

In fact, they saw themselves as the pinnacle of humanity. They had replaced their arms and legs, so they were stronger humans. They had removed their lungs, so did not need to breathe. They had excised entire cortices out of the brains, removing redundant weaknesses like fear. In their place they had recreated man in the image of their computers: strong, efficient, flawless, relentless, even immortal; only organic organs were finite, a cybernetic replacement could be fixed or upgraded.

It was only in their young that they were reminded of what they once were, and perhaps what they knew they still were underneath all their alterations. Allowing eighteen years for an infant to mature before they could be improved upon was an inefficient means of procreation. It did not ensure the survival of the species, and when there were plenty of planets ready and full of full-grown humanoids, the people of Mondas realised there was a far more effective solution to reproduction.

And thus the Mondas humans took to the stars in the interests of their own survival, and whilst they made offspring out of the people they found there, these newly enhanced beings were neither true inhabitants of Mondas, nor even human in most cases. In the ashes of defeated worlds, the Cyberman race was born.

“And do you know what the scariest thing is, Sergeant?” the Doctor said. “I’m pretty sure the Cybermen think you should be grateful. Every species defines survival in different ways, and for humans on Earth, they’re perfectly happy if they live just seventy years and generally get along with everybody. That’s what they call survival, even if they die before they’ve achieved anything. The Cybermen would call that failure, and an inefficient waste of resources. By making you one of them, they turn you into a component part of something that won’t fail, that won’t die.”

“And that’s what they’re going to do to Rose?”

The Doctor gave him a look. “No, Sergeant. That’s what we’re going to stop them doing to Rose.” Then he flicked the soldier a wicked grin.

“There’s something I don’t understand,” Sergeant Cameron said. They had been walking for another couple of minutes in silence by then.

The Doctor nodded. “What’s that?”

A large geyser erupted in their path and Private Doherty changed course quite drastically to take them on a path that would comfortably avoid it.

“If these things go from planet to planet like you said,” Cameron said. “Taking them over and then turning all the people who already live there into more of them, then what the hell are they doing on Erebus? There’s nobody here.”

“Oh.” The Doctor frowned. “Good question.”

“I mean, are they here for the robots? Is this a pit-stop for them?”

The Doctor cocked his head to the side and ruffled his shoulders, which said to Sergeant Cameron that he didn’t really know. “It’s possible, I suppose. They could be cannibalising robot parts here, making improvements. I must say, they don’t look much like the Cybermen I’ve encountered in the past.”

“So what’s their endgame, then?”

“Endgame?” The Doctor said it as if the word was split in two.

Cameron nodded. “Yeah, the overarching plan.”

The Doctor inhaled deeply as another geyser erupted behind them. “Well, how many people are there on that space-station?”

“A few hundred, maybe.”

“Hmm. How about other planets in this system?”

“No, they’re all uninhabited as far as we know.”

The Doctor shook his head.

“Doctor,” Cameron said, putting on a half-cocked grin. “I’m starting not to like it when you don’t have all the answers.”

“You and me both, Sergeant,” the Doctor murmured. He cleared his throat. “Whatever they’re up to, I’m sure it won’t be long before we find out.”

“Why doesn’t that fill me with happy feelings?”

The Doctor turned a look on the sergeant that suggested he was not about to approve of Cameron’s sardonic attitude. But as he began to speak, the metal suddenly began to shake violently beneath their feet, and the words caught in his mouth.

Before they had a chance to flee, the massive geyser smashed through the scrap right in front of them with all the force of a supersonic pile-driver.

Corporal Ryan and Private Spooner were thrown off their feet, and all the others lost their footing. Within seconds the geyser was three yards across and over a hundred high. A rapidly expanding screen of steam enveloped the men as far back as the sergeant and the Doctor, who buried his exposed head in his coat.

After about half a minute, the geyser subsided, and the hot steam in the air began to condense and fall like a boiling rain. The ground stopped shaking, and the tremor stopped creaking through the scrap metal on which seven of the group were still cowering, waiting for the danger either to pass, or to kill them.

One member of the group was already standing.

“Oh my god,” said Private Wells, the first to see who it was.

“Doherty!” Corporal Ryan hissed under his breath.

Sergeant Cameron lifted his head and tapped the Doctor’s steaming shoulder.

Private Doherty had been several yards ahead of the others. He was still several yards ahead of the others, standing right over the spot where the geyser had erupted. In one hand were the remains of the GPS terminal, its plastic covering melted and warped by the superheat. The circuits inside, visible, were sparking.

Private Doherty was holding up his other hand and looking at it. Smoke was coiling into the air from the little black hunks of artificial skin and muscle that still clung to the exposed metal rods and pistons that made up his arm.

The others began to gather around him at a distance, nobody saying anything, as he looked down at himself and saw that his tissue, let alone his clothes, had been seared right off his body. The metallic exoskeleton beneath was completely visible.

A smile teased at robotic lips. “I-I feel naked,” he said.

Sergeant Cameron and the Doctor made their way across the scrap to join the others. There was a caustic smell in the air, like burning rubber, or hair.

“I guess this is what we all look like,” Spooner muttered. “Underneath.”

“At least we know we’re fireproof,” Doherty quipped.

Cameron was surprised it was still Doherty’s voice coming out of the metal humanoid’s mouth, sounding completely normal. It was unsettling.

Even the Doctor was staring at Doherty, wide-eyed.

“How do you feel?” Cameron asked.

Doherty shrugged. “It didn’t even hurt, sir.” He lifted up the GPS terminal and looked at it. “This thing’s history, though. Sorry, Doctor.”

Cameron glanced at the Doctor, but then he saw the Doctor wasn’t even looking at Doherty’s exposed form anymore. He was looking past it.

“Doesn’t matter,” the Doctor said, not looking up. “I think we’re here.”

Cameron turned round again, following the Doctor’s line of vision. The other soldiers stopped staring at Doherty to look. Even Doherty himself turned to see.

There, about thirty yards ahead, was what looked like the mouth of a whale, cresting the surface of a metallic sea. The arch was barely noticeable above the uneven levels of scrap all around it, but looking into the dark mouth of that whale, Cameron saw it was actually a tunnel, and there were lights deep inside.

Doherty sighed. “Well, it’s got to be safer than up here.”

And as if to underline his point, another geyser exploded right behind them.

Cameron nodded curtly. “All right; let’s move.”

NOTES:
Largely unnecessary chapter? Perhaps, but as I was posting this on Gamegossip, I found that even amongst the British posters reading it, not many of them had ever seen "Doctor Who", and even fewer knew anything about the Cybermen. I was going to have a potted history of all the times the Doctor had encountered them from "The Tenth Planet" to "Silver Nemesis", but that wasn't really necessary to this story, whilst some exposition about how the Cybermen came to be, hammering home how they differ both from humans and robots, would be a better way to fill up the time the Doctor and co spend walking. Plus, of course, some action to keep things moving. The fact that the Cybermen have set up their 'base' in an unstable volcanic region literally alive with geysers is important to the plot, by the way.