“Ellison, Cooper, take point,” he said, quietly and calmly. “Spooner, you watch our six. Eyes open, people. We’re not the lions on the prairie down here.”

Private Doherty snorted. “We weren’t the lions even when we were on the prairie, Sarge.” Several of the others grunted in agreement.

“Eyes open; mouths shut,” Cameron said.

They proceeded in silence, the only sounds the low rumbling coming from deeper inside the Cyberman base, and their own feet on the metal floor.

It was the first solid surface the Doctor had walked on since they’d crashed on the planet and he noticed for the first time the strain clambering over all that loose scrap had placed on his knees, which now felt stiff. None of the soldiers seemed to be suffering, but then they wouldn’t, he reminded himself. Even Private Doherty, unrecognisable without his skin, seemed unfazed now he had his orders.

As they went deeper, it got darker. The lights that had looked bright from above turned out to be reflective surfaces, simply shining back at them whatever light they provided. Having blocked out the daylight with their persons, the troops turned to the flashlights located at the ends of their guns. Seven beams hit the silver surfaces and were reflected off again at odd angles. When these reflected beams hit mirrored surfaces themselves, the result was an odd mesh of light effect.

At least the Doctor got a good look at their surroundings. If anything, it reminded him of being swallowed by a giant snake. Not that the Doctor had even been swallowed by a giant snake, but this is what he imagined it would be like, if that snake were made of metal. The walls of the tunnel were made up of scales. There were metal plates of a thousand different sizes all overlapping to make the narrow but tall semicircular passage, about ten feet high. Looking closer, as the beams of light danced across them, the Doctor saw many different types of metal represented, from sheet steel to rusty old slabs of iron, which explained why some were more reflective than others. The plates had been welded or riveted together, then hammered into the right shape. The Doctor’s throat tightened at the thought of the Cybermen being able to build this place with their bare hands. It’s not like they were short of raw materials.

When they reached the end of the tunnel, they stopped.

“Is it me, or is it getting hot?” said Doherty.

The Doctor frowned. “I think we’re at ground level or below here; if anything, it should be getting cooler. But you’re right, it’s shot up several degrees.”

“Why is that, Doctor?” Cameron asked.

“I’m all out of Ts, Ss and Is right now, Sergeant. Sorry.”

He sighed. “All right; let’s take it slow.”

The tunnel levelled out and beyond a perfect square opening was a passage that ran perpendicular to the Doctor’s giant metal snake. The tunnel narrowed as it led up to the opening. The passage beyond was even darker. As he went through the square, something caught the Doctor’s curiosity and he stopped.

“Hang on a minute,” he said.

“What is it, Doctor?” Cameron hissed.

The sides of the perfectly square opening were about seven inches thick, divided down the vertical by a groove. When the soldiers cast their lights on the floor and ceiling, the Doctor saw the groove was missing.

“I wonder,” he murmured.

Then he took out the sonic screwdriver and held the glowing blue tip near the groove. Immediately, there was a clunk deep inside the walls, and the sides of the perfect square opening began to slowly close in on him.

“Ah.” Twisting the end of the sonic screwdriver the other way, the Doctor caused the doors to retract back into the wall. That groove was actually the division between two separate doors; they slid back at different velocities.

“It’s like a blast door,” said Private Wells.

“Yeah, and it’s open,” Corporal Ryan muttered.

“They left the front door open?” said Private Spooner. “This is too easy.”

“Smells like a trap, Sarge,” Private Ellison added.

Private Cooper murmured his agreement.

The Doctor shook his head. “Far more likely is that there are still Cybermen outside and it’s been left open for them to get back in.”

“Yeah, the ones that went back to finish us off,” said Ryan.

This unsettled the soldiers even more than the suggestion that it was a trap, but at least it stopped them looking at the doors and got them back into formation.

“Let’s not wait and see; which way, Doctor?” Cameron said.

“Take the right,” the Doctor replied.

With Ellison and Cooper in the lead once more, and Spooner and Doherty covering the rear, the group moved into the dark passage. It was hotter, but it was a dry-heat, not at all humid. The air tasted like bitter smoke.

They proceeded slowly, even slower when one of those deep rumblings shook past them, or the piercing rushing sounds coursed through the walls.

Eventually they reached another junction.

“Which way now, Doctor?” Sergeant Cameron asked.

“You choose,” he said.

Cameron stared at him. “I thought you knew your way around.”

The Doctor couldn’t help but let out a little chuckle. “Sergeant, I am eternally grateful that I don’t know my way around a Cyberman base, because if I did, that would make me a Cyberman. Now, left or straight on?”

The soldiers looked at each other almost incredulously.

Cameron sighed. “Doctor, how are you expecting to find Rose?”

“Trial and error.”

“Trial... and error?”

“Yes. We look in one room. If Rose is there, yippee, we can leave. If she isn’t, we move onto the next room. Trial and error.”

“Oh, god,” Ryan murmured.

Cameron sighed again. “Cooper, Ellison, head left.”

They walked for another couple of minutes, during which they didn’t see any Cybermen, or any rooms to look in, either. It seemed to be a maze of corridors, which the Doctor found puzzling. The rushing sound was also getting louder.

“Where are they all?” Doherty said.

“Maybe they’re all out looking for us,” suggested Wells.

“Unlikely,” the Doctor said.

“Clearly they’ve got better things to do,” Spooner murmured.

They continued straight on at a couple more junctions, then had no choice but to turn left. The Doctor noticed that this passage, by far the longest one they had followed so far, went in a gradual curve, as if it was encircling the base. Looking back after they’d gone about forty yards, the Doctor couldn’t see where they’d turned into it anymore. It was then that he was struck by a thought.

“Sergeant?” he said in a low voice.

“What is it, Doctor?” Cameron replied in kind.

“I don’t want to alarm you or your men, but in my impatience to find Rose, I may have been rather careless in my considerations of our safety.”

“What are you talking about, Doctor?”

The Doctor bit his lip. “Even if we find Rose, if we get back to that door and it’s shut, then we will be trapped here, whether the Cybermen intended it or not.”

Sergeant Cameron chuckled.

“What’s so funny?” the Doctor asked.

Cameron glanced back at Private Wells, who was still carrying a large case.

“How’s that rocket launcher, Wells?” he called.

“Can’t we just use it already?” Wells growled through his teeth.

Cameron looked at the Doctor and winked.

“Oh,” said the Doctor.

Suddenly, Cooper and Ellison stopped.

“It’s a dead end,” Cooper cried.

Sure enough, fifteen yards ahead of them, the passage came to an end.

“Looks like there’s a ladder, heading down,” said Ellison.

Cameron glanced at the Doctor, but the Doctor knew no more than he was saying. The eight of them squeezed into the end of the passage and peered down into the hole in the floor. There was indeed a ladder, about fifteen feet high, leading down to the next deck, which was, if possible, even darker, and even hotter still.

Cameron wiped the sweat off his forehead and sighed. “Doctor, are you sure, I mean absolutely sure, they will have brought Rose here?”

“Yes,” the Doctor said, fixing him with an unblinking stare. “But I won’t ask you to go any further. I’m grateful that you’ve come as far as you have.”

Cameron snorted. “We better start moving again before I feel the need to order a mandatory hug break. Cooper, Ellison, let’s go.”

One by one, they climbed down the ladder into the insufferable heat. At the bottom, passages went in three directions. There was a curved passage that ran parallel to the one above, but continued where the one above had stopped at the ladder. The other passage seemed to lead straight into the heart of the base.

As they stood there, the floor began to shake beneath their feet. It was more pronounced than the vibrations they had felt on the upper level. This felt like a natural earth tremor shaking the base. In a few moments it passed.

“That felt like a geyser; close by, too,” Doherty muttered, frowning.

“Yes,” the Doctor began to say.

But suddenly he was drowned out by the rushing sound, which was no longer muffled by their distance from its source. The Doctor was almost moved to cover his ears as what sounded like a tornado in a bottle shrieked past. In seconds it too was gone, but as it disappeared, the Doctor realised it was simply moving further away.

“That’s odd,” he said slowly, in a low voice.

“What is?” Cameron asked.

The Doctor didn’t reply. “This way.” Then he set off in the direction from which the noise had come. It took him to the next junction, and turning the corner, he froze. When the others caught up, they froze too.

“Is this what you were expecting?” Cameron asked.

The Doctor shook his head. Emerging from the floor several yards around the next corner was a large pipe, about fifteen inches wide. It snaked out from under the metal grills plating the floor, crept along parallel to the tunnel, then slipped up the side of the wall and disappeared into the ceiling.

Slowly, the Doctor approached the pipe and put his hand near it. He almost touched it, but it wasn’t insulated, and he could feel the heat emanating from the metal pipe from several inches away. He withdrew his hand and frowned.

“What is it, Doctor?” said Cameron.

Suddenly, there was another earth tremor, another geyser.

It passed quickly, then the Doctor counted the seconds until the rushing sound replaced it: four. Lifting his foot, the Doctor pressed his shoe against the hot pipe, and sure enough, as the rubber sole began to soften, he felt the pipe rumble.

Before the rushing ceased, the Doctor snatched his leg away from the pipe, and not because it was starting to melt his shoe.

“Oh, no!” he said breathlessly.

“Doctor, what is going on?” Cameron demanded.

The Doctor turned to him sharply. “Sergeant, I think I’ve just worked out why the Cybermen have built their base in the middle of a geyser field.” As he said the word ‘base’, he cocked his fingers as if to signify quotation marks.

“Don’t do the finger thing; I hate the finger thing. Why have they built their base in the middle of a geyser field, Doctor?”

“To harness its latent energy, of course. Tectonic pressure is nature’s answer to nuclear power. There’s enough potential energy in a volcano to reduce matter to its component atoms, and these geysers are an outlet for several million kilopascals of pressurised tectonic energy. And the Cybermen have harnessed that power.”

“What? Why?” Cameron hissed.

“They’re building a bomb,” Ryan cried.

The Doctor shook his head, following the pipe with his eyes. “That wasn’t a blast door we saw when we came in. It was an airlock.”

It took a few moments to sink in.

“A ship?” Cameron said.

“A ship,” the Doctor confirmed. “This isn’t a base at all. The Cybermen are trapped here as much as we are, but they’re doing something about it. They must be using the force from the geysers to generate enough energy to break orbit.”

“Is that even possible?”

“Theoretically. And now, it would seem, practically, too.”

For a few moments, nobody said anything.

“Doctor, if they get off this planet, what will they do?” Cameron said.

The Doctor turned to him again. “First stop will undoubtedly be that space-station in orbit. They won’t be interested in turning the crew into new Cybermen so much as securing themselves better transport. Of course, they will also cannibalise anything they can find that they think is of use to them, and access the station’s data relay network to look for the nearest potential colonised worlds. Most likely they will destroy the station before Earth men can reclaim it, by which time they will be well on their way to the nearest colony or two. After those have fallen-”

“Okay, I get the picture,” Cameron cut in.

Nobody spoke as there was another tremor, another geyser.

Eventually, Cameron sighed. He turned to Private Cooper. “Cooper, I want you to go with the Doctor. He might need your help.”

“Yes sir.” Cooper nodded curtly.

“We’re splitting up?” the Doctor asked with a frown.

“Doctor, how do we prevent this ship from ever leaving the planet?” Cameron asked, giving the Doctor perhaps the most serious look he’d seen the man give.

“This isn’t what we came to do.”

“You think we shouldn’t try and stop them?”

The Doctor licked his lips. “Okay. You need to follow these pipes down as far as they go. They’re siphoning off the gases released by the geysers, and it looks like they’re channelling it, probably to some sort of gaseous exchange mechanism, maybe a compression unit, which will all lead into some sort of jury-rigged turbine. Destroy any of those, and this Cyberman ship will just be a Cyberman base after all.”

“Looks like you’re going to be coming out of here empty-handed, Wells,” the sergeant quipped. “All right, people; let’s head out.”

As they started to move, the Doctor reached out. “Wait. Sergeant, you blow up a gaseous exchange unit, or a turbine, and they won’t need a rocket to get into space.”

The other troops looked uneasy at the connotations.

“Got any better ideas?” Cameron asked.

“Do you have any timed detonators?”

Cameron nodded sideways. “Left them at the crash-site.”

“What about remote detonators, then?”

“Ditto.”

“Well, you could go back and...” He trailed off.

Sergeant Cameron was shaking his head.

“I see. So this is how it’s going to be, then, is it?”

Cameron cocked his head, a signal for the men to start moving. “Don’t take too long finding Rose, Doctor. Something tells me these Cybermen assholes won’t think we’re just spare parts when we arrive to destroy their goddamn ship.”

The Doctor smiled wanly. “I’m sure you’ll be able to handle them, Cameron.”

“Part of me’s looking forward to it.” He grinned back.

Only Cameron and Cooper were left standing with the Doctor now. The others were waiting at the far end of the passage, where another pipe emerged from the floor.

“Look after them, Cooper,” Cameron said, going to join his men.

“’Sir,” Cooper muttered, watching his comrades go.

“Good luck, Sergeant,” the Doctor called.

Cameron turned on his heel, stepping over a pipe backwards. “Come on, Doctor, you’re a man of science. You don’t believe in luck.” He grinned.

“All the same: good luck.”

“Right back at you, Doctor.” Then he disappeared around the corner.

For a moment, the Doctor and Cooper just stood there, listening to Cameron and the others disappear out of hearing range. Then the Doctor flicked Cooper on his chest-plate with the sides of his fingers.

“Come on. Let’s go.”

NOTES:
A slightly awkward expositional chapter that ended up almost twice as long as envisaged and that I don't think realises its full potential, especially in representing a big turning point in the story. I think it's over halfway in terms of words, but in terms of plot, this was meant to be a pivotal moment. Was slightly worried at the lack of Cybermen in their own base/ship, but have found a simple way to explain that in a couple of chapters time. Little else worth nothing, except for the Doctor's claim that if Sergeant Cameron blows up the Cybermen's turbine, then "they won't need a rocket to get into space" is almost directly lifted from Parker's line in "Alien" after Ripley suggests they blow up the Nostromo: "If we're not out of here in ten minutes, we won't need no rocket to fly through space."