Despite our best efforts, the Tardis continues to shake. "What the hell's it doing?" Donna screeches as I beat the mallet against the console's edge. It only creaks in response.

"Control's not working!" Another tremor knocks the Doctor off his balance. He falls, coming up close to the jar that stores his hand, the liquid around it bubbling far more than usual. "I don't know where we're going, but my old hand's very excited about it."

She looks down at it in disgust and jumps away. "I thought that was just some freaky alien thing! You telling me it's yours?"

Martha grimaces with the effort of holding onto the console. "It got cut off. He grew a new one."

"You are completely... impossible!"

"Not impossible, just a bit unlikely."

One last explosion of sparks knocks us back. The ship falls silent.

Panting, the Doctor and I lock eyes. In an instant we are both on our feet and out the door, finding ourselves in a dark tunnel cluttered with walls of scrap metal and barbed wire. There doesn't seem to be a living soul nearby. "Why would the Tardis bring us here?"

"Oh, I love this bit," Martha says under her breath.

Donna sends her a strange look. "Thought you wanted to go home."

"I know, but all the same. It's that feeling you get..."

"Like you've swallowed a hamster."

We don't get a chance to react to her comment. A shout alerts us and several men appear, all dressed in army green with their guns aimed at us. "Don't move! Drop your weapons!" squeaks the boy leading them.

Leading by example, the Doctor raises his hands in surrender and turns them to show that they are empty. "We're not armed. Look, no weapons, never any weapons, we're safe."

"Look at their hands," another says. "They're clean."

"All right. Process them. Him first."

They seize the Doctor. My body moves after his as if on instinct, trying to block their path, but the gun is turned on me instead. "It's all right. Stand down, Inara," he warns. I begrudgingly step back, clutching at my still-injured wrist. "What's wrong with clean hands?"

"What's going on? Leave him alone!"

He is marched over to a giant tank of a machine, where they force his arm down a metal chute. "Something tells me this isn't about to check my blood pressure. I—" Whatever he is about to say next is cut off by his own screaming.

My heart races. Panicked, I swiftly grab the gun from the boy and turn it on his friends. "What are you doing to him?"

"Everyone gets processed."

"It's taken a tissue sample," the Doctor gasps. "Ina— Ow, ow, ow! And extrapolated it. Some kind of accelerator?"

"Get him out of that thing right this second or I swear to all the Gods, I'll—"

With a loud clanking of parts, the chute opens and he is released. My weapon falls, forgotten, as I rush to his side. I take his hand in mine and insistently pull it towards myself for examination. A thin streak of read covers the back of it, spotted with emerging droplets of blood. He gapes at it in bewilderment. "What on Earth? That's just..."

The glass doors of the tank slide open. From the blue light within, a girl emerges. She wears the same colours as our attackers, and her long blonde hair is pulled back in a ponytail. Staring around her surroundings in wonder, she steps out. A gun is pushed into her hands.

We all stare at her, speechless. Although I suspect she already has an idea, Martha quietly asks him, "Where did she come from?"

"From me."

"From you?" Donna repeats. "How? Who is she?"

I can't tear my gaze from the girl. There's something about the shape of her face, the shade of her eyes, her expressions. Everything. I've never met her before and yet I know her on sight.

"She's— Well, she's— Well... she's my daughter."

As if on cue, the girl finishes loading her gun. She fixes us with a brilliant smile. "Hello, Dad."

And with that, she is gone, following the boy. "Are you primed to take orders, ready to fight?" he asks her, suddenly oblivious of our presence.

"Instant mental download of all strategic and military protocols, sir. Generation Five Thousand Soldier, primed and in peak of physical health. I'm ready."

Donna blinks. "Did you say 'daughter'?"

He hums in response, still watching after her. "Technically."

"'Technically' how?"

"Progenation. Reproduction from a single organism. It means one parent is biological mother and father. You take a sample of diploid cells, split them into haploids, then recombine them in a different arrangement and grow — very quickly, apparently."

I still can't wrap my head around it. All I can do is stare at her, praying for someone to jump out and declare it all a joke. Instead, I hear her whisper, "Something's coming."

Sure enough, shadows loom along the brick ceiling up ahead. I know to duck even before the shooting starts, dragging the others down with me. We watch in confusion as creatures appear at the curve of the tunnel, scaled and purple with bubbling cylinders of green liquid fixed to their faces where their mouths should be. "It's the Hath!" the boy shouts. "We have to blow the tunnel. Someone get the detonator!"

They're already advancing too quickly. I reach for a fallen gun but the Doctor pulls me back. "I'm not detonating anything!"

With my back to the fighting, I have no chance to turn before I am grabbed from behind. I manage to push my attacker off but end up falling to the floor.

"Inara!" The Doctor's efforts to help me up are only a hindrance. Our brief distraction allowed the creature to get past us, taking Martha instead. She is already halfway back to the other side of the tunnel, dragged away screaming.

"Blow the thing!"

"Martha! No, don't!"

But the girl has already pushed the button. We have no choice but to follow, racing away as far as we can get. The heat of the explosion knocks us off balance, blazing the tunnel with fire and sparks. When we emerge again, the path towards Martha is completely clogged with debris. "You've sealed off the tunnel. Why did you do that?" the Doctor yells.

She frowns up at him. "They were trying to kill us."

"But they've got my friend."

Her expression growing cold, she nods back to her comrade who is doubled over and gasping for air. "Collateral damage. At least you've still got them, he lost both his men. I'd say you came out ahead."

"Excuse you!" I snap.

"Her name's Martha, and she's not 'collateral damage', not for anyone! Have you got that, GI Jane?"

Donna's harsh response is enough to shut her up. Still bristling with anger, the Doctor starts towards the blocked tunnel. "I'm going to find her."

He is immediately stopped by the click of the boy's gun being re-aimed right at us. "You're going nowhere. You don't make sense, you lot — no guns, no marks, no fight in you..."

My already-short temper boils over. Pushing past them, I storm right up to him and rest my hand right over the barrel of the assault rifle. "I'll show you the fight in me, mate," I seethe. "If you point that thing at my friends one more time, you will not like where I put it next. Have you got that?"

He gulps. Then, taking a deep breath, he flexes his finger against the trigger. "Take your hand off."

"Just do as he says, Inara," Donna pleads. "We'll find another way to get Martha back, but this isn't worth losing your bloody hand. Don't be stupid."

I look to her, to the wall of rubble, and then back to the boy who is trying so hard not to appear terrified. With one last glare, I release the barrel. He swallows nervously and nods to the winding tunnel. "I'm taking you to General Cobb. Now, move."

—

As we walk, my hand brushes against the Doctor's. I spare a glance down at it to find that the wound has almost completely healed. He doesn't register my brief touch. If he does, he's good at hiding it. I catch a flicker of pain in his eyes but I don't know if it is because of me or the girl walking ahead of us. I can't imagine what this must be like for him. After all these years, finding himself with another child is far from expected.

"I'm Donna. What's your name?"

She pulls an awkward smile, leading the way down a series of stone steps. "Don't know. It's not been assigned."

Shooting us a bewildered frown, she tries again, "Well, if you don't know that, what do you know?"

"How to fight." It's as if the answer is obvious, like there is no logical alternative.

"Nothing else?"

The Doctor arches an eyebrow. He hasn't taken his eyes off her yet. "The machine must embed military history and tactics but no name. She's a generated anomaly."

"'Generated anomaly'," Donna slowly repeats. "Jenny-rated. Well, what about that? Jenny!"

"Jenny. Yeah, I like that, Jenny."

Falling back into step with us, shoulders now jostling in the narrow corridor, she says, "What do you think, Dad?"

"Good as anything, I suppose," he mutters.

"Not what you'd call a natural parent, are you?"

I pause, giving her arm a sharp pinch. "Oi, stop it. Just leave him alone."

Her startled gaze lands on me. Before she can argue back or get revenge for my little attack, the Doctor brings his hand to my back and urges me to keep walking. "Donna, they stole a tissue sample at gunpoint and processed it. It's not what I'd call natural parenting."

"Rubbish," she scoffs. "My friend Nerys fathered twins with a turkey baster. Don't bother her."

"You can't extrapolate a relationship from a biological accident."

"Uh, Child Support Agency can."

His patience is wearing thin, made clear by the absentminded tracing of his hand against my back. I reach behind me to take it but he assumes that I want him to let go. Before I can think it through, I pull his hand back and secure it in mine. My act of kindness causes his hardened glare ahead to falter. "I— Look, just because I share physiological traits with simian primates doesn't make me a monkey's uncle, does it?"

Jenny comes to a sudden stop. "I'm not a monkey!" she snaps. But he walks right past her without a second look. "Or a child."

Sending her an apologetic grimace over my shoulder, I lean in to whisper to him, "Doctor, I know this is hard, but—"

"I don't want to talk about it."

"Well," I answer with a sigh, "'it' wants to talk to you. So I'd start reconsidering."

—

The tunnel finally starts to open up, the sound of chatter reaching us. "So where are we? What planet's this?" the Doctor asks, quickening our pace to catch up to the young soldier.

"Messaline — well, what's left of it."

This is unlike any military camp I have ever seen. It looks like the inside of a theatre, judging by the ornate arches above a raised platform, although it has been stripped bare of the seats. Camp beds and tents dot around the small space. Up in the boxes and on the stage, soldiers stack crates upon crates of supplies and ammunition. They all wear the same greys and army greens. When I look close enough, I can recognise similarities between them. This entire base must be made up of clones.

Donna seems to have noticed our surroundings as well, gaping around at them in complete awe. "But... this is a theatre."

"Maybe they're doing Miss Saigon," the Doctor half-heartedly jokes, dropping onto one of the empty beds. Our hands are still connected, resting atop the barred headboard. I give his fading scar a light, experimental poke, earning a small wince from him — not, I realise, out of pain, but memory. At the sight of my guilt, he smiles weakly and gives my hand a squeeze.

"It's like a town, or a city, underground. But why?"

He jumps up again at the return of the boy, or rather the elder soldier who leads him, white-haired and rugged from a lifetime of warfare. It is something I can recognise without needing to ask, I have seen the same look in countless people. "General Cobb, I presume?" the Doctor chirps.

"Found in the western tunnels, I'm told, with no marks," he gruffly remarks, coming to a stop before us with his hands clasped behind his back, at ease. I find myself taking on the same stance as if on instinct. "There was an outbreak of pacifism in the Eastern Zone, three generations back, before we lost contact. Is that where you came from?"

"Eastern Zone, that's us, yeah. Yeah, I'm the Doctor. This is Inara, and this is Donna."

"And I'm Jenny."

Cobb is oblivious to the Doctor's despairing look her way, too caught up by our claimed origin. "Don't think you can infect us with your peace-making. We're committed to the fight, to the very end."

He shrugs. "Well, I can't stay anyway, gotta go and find my friend."

This only puts him more on the offence. "That's not possible. All movement is regulated. We're at war."

"Yes, I noticed. With the Hath. But tell me — 'cause we got a bit out of circulation, Eastern Zone and all that — so... who exactly are the Hath?"

All we receive at first is a solemn nod, a gesture for us to follow him as he starts to wander around this tiny base. "Back at the dawn of this planet, these ancient halls were carved from the earth. Our ancestors dreamt of a new beginning, a colony where Human and Hath would work and live together."

Pursing my lips, I look around at their war camp. I don't expect the onslaught of memories from my childhood, growing up in temples devoted to strategy against such a species, treating the casualties and mourning the dead. My hand finds the Doctor's again and clasps it tight enough to bring his focus down to me. His brow furrows but I shake my head. "So what happened?"

"The dream died, broken along with Hath promises. They wanted it all for themselves. But those early pioneers, they fought back. They used the machines to produce soldiers instead of colonists and began this battle for survival."

Donna has stepped up onto a crate, peering up at the latticed window, which lets in no light. "There's nothing but earth outside, why's that? Why build everything underground?"

"The surface is too dangerous," the boy explains.

"Well then, why build windows in the first place?" She then points to a silver plaque nailed into the wooden wall panels, engraved with a series of numbers. "And what does this mean?"

Cobb draws himself up tall with pride. "The rites and symbols of our ancestors. The meanings... lost in time."

This catches the Doctor's interest. "How long's this war gone on for?"

"Longer than anyone can remember. Countless generations, marked only by the dead."

Jumping down, she rejoins our group. "What, fighting all this time?"

"Because we must," Jenny quickly replies. I can't help but smile to myself, noting the precocity that I'm sure the Doctor had when he was just a boy. "Every child of the machine is born with this knowledge. It's our inheritance. It's all we know. How to fight... and how to die."

In an effort to clear my head, I take another look around. "And you said there are zones, right? How big is this war, exactly? Can I take a look at your maps?"

Cobb seems to be taken aback by my request but nods, eyeing me warily as he leads us to desk just below the stage. A holographic image pops up from it, displaying a gridded map. To my surprise, the entire thing consists of four actual chambers and some simple tunnels that take up only fifty quadrats. The Doctor and I share a confused glance. "Does this show the entire city?" he asks.

"Including the Hath zones?" I add.

"Yes. Why?"

Still frowning, I mumble, "Not sure how you've managed to have a war this long, considering..."

All eyes land on me. Cobb bristles and indignantly retorts, "'Considering', what?"

Feeling put on the spot, I shrug and awkwardly point to the map. "Well, it's just a bit... small."

"No matter," the Doctor sternly continues. "It'll help us find Martha."

"We've more important things to do," the boy argues. "The Progenation Machines are powered down for the night shift, but soon as they're active, we could breed a whole platoon from you three."

Cringing at the thought, I stifle a chuckle at the sight of Donna's disgusted expression. "I'm not having sons and daughters by some great big flipping machine!" She sighs when Jenny turns to glare at her. "Sorry, no offence but, I mean, you're not real."

The girl scoffs. "You're no better than him! I have a body, I have a mind, I have independent thought. How am I not real? What makes you better than me?"

"Well said, soldier. We need more like you if ever we're to find the Source."

Once again intrigued by General Cobb's words, the Doctor speaks up with an air of mockery, "Ooh, the Source! What's that then? I like a Source, what is it?"

"The Breath of Life."

"And that would be..."

"In the beginning, the Great One breathed life into the universe. And then she looked at what she'd done and she sighed."

Jenny chuckles, "'She'? I like that."

Our eyes meet and I offer a smile. "Once this is all sorted out, you come to me. I know plenty about Goddesses if you're interested."

"Right," the Doctor tersely interrupts before we can derail the conversation, "so it's a creation myth."

"It's not myth. It's real. That sigh, at the beginning of time it was caught and kept as the Source. It was lost when the war started but it's here, somewhere. Whoever holds the Source controls the destiny of this planet."

"Ah!" We all jump, caught off-guard by the Doctor's sudden cry. He swipes a hand through the map and watches it flicker and buzz for a second before returning to normal. "I thought so. There's a suppressed layer of information in this map. If I can just..."

He directs his sonic at the projector disk below it. The map zooms out and a whole new set of rooms and corridors expand from the initial markings. At the very top lies a circular chamber, from which every path seems to curl out of.

"What is it?"

"See? A whole complex of tunnels, hidden from sight."

Cobb takes in the new sight in fascination, murmuring, "That must be the lost temple. The Source will be inside. You've shown us the way. And look, we're closer than the Hath. It's ours!" He turns sharply, addressing his soldiers. "Tell them to prepare to move out. We'll progenate new soldiers on the morning shift, then we march! Once we reach the Temple, peace will be restored at long last."

The Doctor is quick to block his path before he can give any further commands. "Call me old fashioned, but if you really wanted peace, couldn't you just stop fighting?"

I fight the urge to roll my eyes. "And call me a pessimist, but maybe not all wars are as simple as that."

"We can only stop when we have the Source. It'll give us the power to erase every stinking Hath from the face of this planet."

Grimacing, I take an awkward step away from the General. "Yeah, never mind."

The Doctor is significantly more disturbed than I am, at least outwardly, and snaps, "A second ago, it was peace in our time, now you're talking about genocide?"

"For us, that means the same thing."

"Then you need to get yourself a better dictionary! And when you do, look up genocide. You'll see a little picture of me there and the caption will read 'over my dead body'!"

Growing impatient, the General hastily rebukes him, "You're the one who showed us the path to victory. But you can consider the irony from your prison cell. Cline, at arms!"

The young soldier points his gun at us but Donna hurriedly raises her hands. "Oi, oi! All right! Cool the beans,