Invasive Species

7

Beneath the underground tunnels was a whole other layer, a crisscrossing maze of intricate and almost impossibly narrow passages, just big enough to fit a person through one at a time. Walls lined with living, breathing, claustrophobic roots. Clara inched through the tunnels keeping a tight grip on the Doctor, terrified that they were going to crush them to death with a moment's notice; for that reason, she was staying ready to turn them intangible as quickly as possible, in spite of the Doctor's protests about her distaste for walking through walls.

"Why do we always end up underground?" Clara grumbled, having to walk almost sideways as she was pulled through the darkness by Thirteen, who was holding the only torch. "Baby-Faced Fletch lived underground, the doorway to the Unnameable was underground, and now this ridiculous tree-lair is underground."

"Not sure where else you'd expect a tree-lair to be."

"I don't know. In the branches, in the sky? Because, right, science, yeah…" she paused.

"Your reason is 'because, right, science, yeah'?"

"No, I'm thinking… okay, so, trees… they get food through the leaves, right? And the branches? So why wouldn't the kidnapped people be in the branches?"

"Coo, I'm going to ask you a question, and I need you to answer me honestly – what grade did you get in your Biology GCSE?"

"Okay, first of all, I sat my Biology GCSE at least sixty years ago. Second of all, I got a C. I know all the important stuff."

"The important stuff being, what? Genitals?"

"Yes, exactly. Not plants. When would knowing about the anatomy of a plant ever come in useful?"

"I don't know, how about at this exact moment? Also, you teach English! That's the ultimate useless subject. It's all made-up. At least in History, the things actually happened. Like, Winston Churchill did say all those racist things about Indian people. But Puck did not say all those hilarious things about rich Athenians, because he's not real. And you need to start sitting in on Cameron's lessons – they absorb sunlight through the leaves, they get nutrients through the roots. So the people are going to be down here, with the roots."

"Well, you say that," Clara began, having to walk sideways to fit through the passage, "But I've always got you to know things for me."

"And what about when you don't have me? Like, what if I'm somewhere else? I might go to watch a movie you don't want to see, and obviously since I respect your choice to not see a movie if you don't want to, well, I wouldn't be there. It would be a dire situation with no recourse."

"Here I thought you were going to say what if you died, or something. Why can't I just go to the cinema and get you?"

"Because! That would be rude. You can't just walk into a movie halfway through, what's the matter with you?" Clara rolled her eyes, not that the Doctor could actually see her.

"This is a stupid conversation, I always go with you to the cinema, even if I don't like the film. How am I supposed to appropriately critique something without having seen it? I need to know which bits to make fun of you for enjoying, specifically."

"Oh, you are so thoughtful."

"My point is-"

"I didn't realise you were making a point."

"-if the trees eat through their roots-"

"Which, they do."

"-then where are the – EURGH!" she shrieked and jumped backwards, but this was impossible in the cramped crawlspace, so she wound up banging her head against a root and no further away than the horror which had triggered her outburst.

"What?" the Doctor turned, alarmed. As she did, she cast the full beam of her torch across a ghastly, human face only just visible protruding through the limbs around them. "Well whaddaya know, you just answered your own question. There's a person, in the roots."

"Fuck!" she exclaimed, "Is he dead!?"

"I don't know – hold this," the Doctor handed her the torch and awkwardly fumbled while she retrieved her sonic screwdriver. The gap was so thin she couldn't lift her arms up all the way, making just reaching into her own pockets tricky. Clara found herself trying not to look for any more faces or body parts sticking out of the walls. The Doctor scanned the face with the purple-lighted sonic and listened carefully. "He's alive. Suffering from symptoms of sustained blood loss. I'd say he's been here a few days. But that's good, that means there's a big chance of being able to rescue people."

"Why is he unconscious?"

"Probably anaesthetised. If they panic they'll lose blood quicker because their hearts beat faster. Keeping them calm keeps the trees in control," she explained her hypothesis. "Also to stop them from escaping, like how Venus flytraps are sticky, I guess. These roots look awfully strong…"

"What do we do? Free him? I could phase him out?" Clara suggested.

"And then what would we do with him? Leave him here in this passage? They'll pick him back up again as soon as we're gone, and he won't make it to the exit without being retrieved."

"So we're just supposed to leave him here? And however many thousands of others are also embedded in the walls?" Clara challenged her.

"We don't know that there's not some sort of… failsafe. What if pulling him out of the tree is like taking him off life-support, ripping out IVs? There has to be something in there to keep him asleep and withdraw blood."

"Like what? Tiny, wooden syringes?"

"What I'm imagining isn't dissimilar to tiny, wooden syringes," said the Doctor, "We need to leave him, keep moving. Destroy the heart, locus, life-source, whatever, of these trees. C'mon." Clara didn't move, so the Doctor softened her tone considerably and touched her arm. "Coo, this is the best way to help. The ends justify the means."

"You know it was Machiavelli who said that, and he was talking about dictators using any means necessary to maintain control of their subjects."

"I think you'll find it was me who said that, and Machiavelli overheard me and liked it so much he made it part of his little 'ideology,'" she explained, taking the torch back from Clara and holding her hand again so that they could proceed, leaving the plant-prisoner behind to live on in the walls, like Han Solo frozen in carbonite. "He really has no scruples."

"What did you expect?"

"It's not like I was there to talk to him, I wanted to hang out with Leo. Anyway, he ended up accusing me of murdering Medici, so, y'know, that happened. It was a long time ago. I actually came up with that phrase back in school, I was arguing with somebody about this ad hoc experiment I was doing involving a black hole machine – sort of the Time Lord equivalent of mixing Mentos and Diet Coke. There was this whole explosion and maybe the fabric of reality as we know it was a little bit threatened – but I fixed it! And I was like you know what? The ends justify the means."

"Right. And what were the ends, exactly?"

"I learnt not to build black hole machines for fun. Only when necessary."

"I'm so glad you didn't get a job in the science department sometimes…"

"You never know, maybe they'll put the Renaissance on the syllabus. I can tell everybody my Machiavelli-accusing-me-of-murdering-Giuliano-de-Medici-and-the-Pope anecdote."

"Mm, you do that. I'll be sure to visit whatever institution they throw you in. Remind me not to ask you for help historicising the Renaissance."

"Do you even have any non-Shakespeare Renaissance texts to study?"

"Not right now. Maybe I'll throw in a bit of John Ford. Incest, baby eating, vilification of Catholicism – all that good stuff."

"You have fun with that."

"I'll ask Tom what he thinks. In fact, I won't ask Tom what he thinks, because I know as soon as I bring up Whore, he's going to start talking about Malfi, like they're somehow equivalent. Best to forget the whole thing."

"I would personally like to forget the existence of both of…" she slowed to a halt.

"What?" The Doctor took her elbow and pulled her a foot or so further, pointing out another face in the root-mesh. Unlike the last one, however, this one was sickeningly familiar: it was Jakub. Clara didn't say a word as the Doctor drew out her screwdriver once again, checking him over.

"He's alive. Also suffering symptoms of blood loss, but not as progressed as the other guy."

"Right, so, they're down here in a random order?" Clara asked, "You'd think it would be a last one in, first one out kind of deal."

"I'm not gonna pretend I understand how these trees store their food. It could be alphabetised, for all we know. Or it could be… to do with iron content? Maybe the deeper they are, the more nutritional?"

"We can't leave Jake here," said Clara.

"We've got even more problems if we try to free Jake than if we try to free anybody else. If he wakes up, he'll recognise us, and then our cover's blown. We're meant to be laying low, not advertising the fact we protect the world from alien threats. And besides, the passage is way too narrow to carry him, and we can't just leave him on the floor here."

"Great. So, once again, 'the ends justify the means.'"

"We don't know that taking him out won't kill him while the trees are still alive. Do you really think that's a risk we should take? And then haul him around with us, retcon him if he wakes up? I don't like using retcon at the best of times, let alone on teenagers with their developing brains, and especially not ones who smoke pot. I don't know how marijuana interacts with powerful, selective amnesia drugs." Clara didn't speak, she was thinking, trying to come up with a very convincing rebuttal to the Doctor's many, salient points. "Okay. I'll show you what I'll do." She started searching through their bag again, fumbling for a while until withdrawing a stick of chalk. She showed the chalk to Clara and then used it to mark a large 'X' on one of the roots wrapping around Jake. The white 'X' stood out quite well against all the blacks and browns of the underground. "Now we'll be able to find him right away on our way back out. I could even wedge a glowstick in there, if you want?"

"Do you have glowsticks?"

"Always. In case of an emergency."

"What kind of an emergency? Like, we have to go to a rave?" Clara asked incredulously.

"No. They're very useful."

"For raves."

"Not for raves – do you want a glowstick or not?"

"Do you have any water?"

"Not at the moment."

"Alright. So, glowsticks are vital supplies, but water-"

"I haven't restocked! We drink the water, but we don't use the glowsticks."

"Do you think that might be evidence to the effect that the glowsticks aren't vital supplies?"

"You know what?" she was annoyed now. She took the bag from her shoulder again and searched through it until drawing out a glowstick. She cracked it and the green illumination spread out from the centre. "Are you happy now?" she brandished it in Clara's face, who leant away. Then she wedged it in the tree trunks above the 'X'. There was no way they'd lose Jake now.

"That has to be the most passive-aggressive glowstick-cracking in history."

"Oh, you think that was passive? That was not passive. That was full, unadulterated aggression, Oswald."

"Wow. I am shitting myself. You are truly a force to be reckoned with."

"You are such a waste of my time. I don't know why I bother with you. Come on, I'm getting tired of these close quarters; sooner we escape, the better. Put some distance between us." They kept walking, the Doctor wondering if that was maybe a bit too harsh when Clara didn't come up with a response – though she stood by the glowsticks coming in handy. What if they needed to mark a trail, Hansel and Gretel style? Or they were somewhere dark but ran out of batteries.

"Hey," Clara interrupted her thoughts on the many applications of glowsticks, "There was something on the news about UNIT showing up."

"Doesn't surprise me."

"Well… alright, colour me stupid, but I thought UNIT disbanded, like, decades ago. I remember when you regenerated and we ran into them in the library, there were less than half a dozen. They were less important than Undercoll. And now, they're being called out in force?"

"They're having a resurgence. During the Manifest Crisis, they were deemed inept and replaced by the Hazard Control Corps, okay? The HCC was specifically to deal with the Manifests. The British government would have shut them down altogether, but since they technically operate as a part of the UN, there's UN legislation in place meaning all the member states have to have an active UNIT sect. But in 2029, your wonderful sister managed to finally synthesise a widespread cure for the existing Manifests. After sixteen years the Crisis ended and the HCC dwindled and disappeared less than a decade later – I guess you guys taking down their megalomaniac leader really did a number on them. So the Manifests are gone, but alien threats persist, as you can see by this… whole thing. The crown doesn't really want to give Undercoll more power, so they re-invest in UNIT, and for the last thirty-ish years they've been building up a presence again."

"Huh. Then who's in charge of them? Not Kate, surely? She'd be ancient, like, a hundred."

"Yeah, um, I'm pretty sure she died…"

"Oh."

"I don't know who's in charge. Maybe it's another Lethbridge-Stewart? They could be building a dynasty – a hundred years of dominance over the extra-terrestrial intelligence service. I've just been hanging out with you all this time, I've sort of lost touch with my favourite branch of the military industrial complex."

"You've been 'hanging out' with me?"

"Yeah. It's a low-key thing, y'know?"

"Right."

"Nothing heavy. No commitment." Clara laughed a little. "I freeze up at the thought of commitment, so if we can keep things light and breezy for the time being, that'd be swell."

"Light and breezy like our mortgage, contract salaries and teenage ward?"

"Nothing says 'chill' like a series of legally binding agreements. Honestly, though, you might have something there. About UNIT, I mean. I should probably look into them, see exactly what they're about these days. Might come in handy if they ever get wind of an attractive, alien teacher and her equally attractive, superpowered wife hiding out in Brighton. Didn't Oswin delete all record of you from their databases?"

"Pfft," Clara just scoffed, "Like I have any idea what Oswin does. She could have, I suppose, it would be sensible since I'm an unregistered Manifest. Makes me very dangerous and volatile that I don't have a clandestine paramilitary group tracking my every move in an effort to stop me from killing everyone, and/or biologically reproducing and passing on 'the gene,'" she did inverted quotation marks with her fingers. The authorities were absolutely petrified of those Manifests who had not been cured in 2029 reproducing, since the Manifest DNA corruption was hereditary after someone developed the initial mutation.

"Hey," the Doctor whispered, "I think I see something up ahead."

"Better be a way out of these bloody tunnels."

"I wouldn't bank on it, Coo…"

The Doctor was right. The web of underground tunnels did all lead to one, central point, directly beneath the main tube station, and the abomination they found could certainly be described as similar to a heart. A vast, pulsating shape, the same width as the gigantic tree towering over the city, was suspended in an enormous cavern by a thousand blood-sucking roots. The roots worked like arteries, feeding the mass as it grew and oozed, coagulated blood dripping down from its porous, organic surface. It must be at least a hundred metres across, the pair of them like ants by comparison. And that was the alien entity trying to take over Brighton? That was what they were supposed to be destroying?

"That thing grew out of the dust from the meteor shower?" Clara asked, staring up at it. So they kidnapped people were stored in the tunnel walls, roots burrowing into the skin, and their blood was taken to feed the 'heart.' They stood on a precarious ledge overlooking the chamber, the sphere hanging in front of them. If they fell, that would be it, the drop was too far to survive.

"It sure looks that way."

"Well, great. How long until the roots start attacking, then?" The Doctor didn't answer. "Do you have a plan? Apart from, I don't know, throwing glowsticks at it? Shooting it with deodorant flamethrowers?"

"We should have brought some explosives… see, this is why you shouldn't have forbidden me from keeping TNT in the house."

"If you'll remember correctly," Clara began, "I initially did not forbid it – it was only after the incident where you put a stick of dynamite in the downstairs toilet 'for a joke' that that rule came into effect. It still doesn't flush properly, even after getting it fixed."

"Okay, so I made one mistake, big deal." Clara rolled her eyes. "Let's brain storm."

"This is the problem with improvising everything – you need to come up with better plans. 'Plan rigorously, but allow for happy accidents.'"

The Doctor scoffed, "What idiot said that?"

"David Lynch."

"Oh, and you think David Lynch plans things? The sixth season finale of the third Twin Peaks revival speaks for itself, Clara." Clara cleared her throat and then pointed at the gigantic tree monster. "Now you want my ideas? You don't wanna call David Lynch, see what he thinks?"

"Very funny. You know he has my number blocked because I asked him to explain Mulholland Drive to me. Don't need to go rubbing salt into the wound."

"Alright, alright… it's a heart, so, all we need to do is stop it. Or disconnect it. This thing is what's controlling and feeding all the trees on the surface – we already established they don't photosynthesise. Without an attachment to this brain-thing, all the other trees will die."

"Is it a heart or a brain?"

"A brain-heart."

"Brain-fart?"

"I'll show you a brain-fart… jerk…" she muttered.

"What you're saying is we need to rip out all of these roots?"

"Hypothetically speaking. I don't see how we could feasibly-" Clara held out her hand towards the blob and one of the roots tore itself violently free. It flailed in the air, spewing blood like a severed tentacle. "No, Coo, I don't think that's a good-" A second root tore itself away from the sphere. "Clara," the Doctor said firmly, "That's dangerous. Two, three roots, sure – but there's over a hundred, and they're still moving, you can't-"

"I think it's actually you who worries too much."

"The telekinesis is dangerous, you know that, that's why you don't use it for things like this – do you want another aneurysm?"

"No, of course I don't want an aneurysm, but I also don't want the two-thousand people down here and the other ten-billion people up there to die," she said, psychically ripping out another root. They were both right. Killing that thing would be an extreme and deadly exertion, but without a bomb, without the Lightning Girl, without the Bad Wolf, at that moment 'the Phantom' was the only hope they had to eradicate the trees.

"I really think I might be able to use these glowsticks to throw together some kind of IED-"

"First of all, that's ridiculous; second of all, even if it wasn't ridiculous, I don't think detonating a bomb in these very fragile tunnels is a good idea," Clara said, pulling out a fourth and a fifth. It reminded her strangely of all the blackhead videos she had been watching that very morning, and the 'heart' was just a gigantic, acne-ridden face. "We could bring the whole city crashing down." Soon she had ripped ten roots away, causing the mass to ripple like bubbles were popping on its veneer. But while pulling the roots out wasn't too difficult, the real trouble was keeping them from latching on again. It was a constant battle as she kept snapping them to stop this, and incrementally the amount of energy Clara was exerting rose and rose and rose.

"Uh, worried as I am, my darling, we sort of have another problem," the Doctor interrupted while Clara tried to focus. The Doctor was backing away from half a dozen tendrils coming out of the walls, defenceless except for her aerosols and lighters. Clara sent a blast of telekinetic energy at them, knocking them away for the time being, but within seconds they were regrouping to come in for the attack.

"Get over here and let me phase you."

"What? Let you hurt yourself even more? This is risky enough already! I couldn't-" A root struck for her. Clara dropped what she was doing with the heart and grabbed the Doctor's wrist, dragging her out of the way (once again) and turning her intangible in the process. "They're going back for the thing!" Thirteen pointed at the heart. Clara's attention was split between trying to keep them both from getting mauled and trying to kill the trees. "This is such a bad idea!"

"You're supposed to be supportive of me, you know! This is hard!"

"Well – I – gah! Okay, okay – just, take deep breaths, focus, uh, push?"

"Push? Push what!?"

"It's just what people say in movies!"

"In labour scenes, maybe – I'm getting a headache."

"Focus on the trees, we have to save the city. You have to save the city. I mean, not to put a lot of pressure on you or give you any, uh, performance anxiety, but… you got this, is what I'm trying to say, if these trees would stop attacking me," the Doctor spoke very haphazardly because the roots kept striking and then sailing straight through her body, which was a nauseating feeling. She would never understand how Clara could stomach intangibility without flinching. "Are you feeling supported yet?" Clara was trying to focus. "Um… do you remember when we went to Akhaten and you did that thing with the leaf? Well, this is just like that, only on a smaller scale. And you did that, so you can do this super easy. Or, maybe not super easy, but relatively easy? A certain degree of ease? It's possible, is my point. I hope it's possible. I mean – what am I saying? You can do anything you put your mind to. Achieve your dreams! That's why we have feminism, right? Just think of the big tree heart like it's the patriarchy and you're crushing it using your mind because you're, erm, a strong independent woman. Or something like that. I always find the key to success is visualisation, so, just visualise yourself winning and you're bound to win, winner. Just like Charlie Sheen, although, maybe not exactly like Charlie Sheen… you know, I think that was a bad comparison to make. At the end of the day, you're in charge of your own narrative, and you need to take back control. From the big tree thing. Show it who's boss! You know what they say, when life gives you trees, make tree-ade. I swear I used to be better at impromptu speeches – oh, jeez, I think you made it angry."

The blob was now writhing in the air as Clara plucked the roots out one by one. Soon enough it would be too heavy for the remaining roots to support it, and it would go crashing to the ground. But Clara fell to her knees.

"You are doing so great, Coo," the Doctor resumed whatever nonsense she had been spewing, sure that Clara wasn't actually listening to her words and just wanted the sound of her voice. "Just stick at it, we'll be done in no time. That is to say, you'll be done in no time, because you're the real hero; I'm only here to provide moral support, witty repartee, and somewhat outdated pop culture references. But you're on fire. Going for gold. All the medals, in fact, even the last place medals – not that you're in last place, and not that they even give medals for last place, but you'll have a whole shelf of participation trophies, I'm sure. I'll make you a trophy. We can get an entire cabinet of trophies just as soon as you put this tree in the ground for good. Deeper in the ground, obviously we're already in the ground…" Clara's nose began to bleed. "Keep calm and focused, okay? We're one mind about this, I think. And your mind, or brain, is going to be fine, you're definitely not going to have a haemorrhage. Whatever you do, don't think about haemorrhages, or think about much at all – except for the tree, which we need to kill. You need to kill. Am I pressuring you too much?" Clara did not reply, scrunching up her face in concentration. Roots thrashed in the air around them, unable to re-attach themselves, unable to strike their assailants.

The walls began to rumble around them. Ripping out the roots was making the already-precarious tunnel system even more unstable. The Doctor dreaded to think what would happen when the bleeding heart fell to the ground, the thing looked more than a little heavy. Watching it struggle dimly reminded her of watching the stern of the Titanic as it sank beneath the sea, even if it was only comparable by sheer scale.

"You're so close," she said, raising her voice over the sound of the trembling earth, "You can do this. I believe in you, more than I've ever believed in anything or anyone. Who cares about the dumb Lightning Girl? There's only one superhero I'm interested in, and that's the Phantom. But only this half of the Phantom, not that other, lame half who can't go out in the daylight. The better half. The better half who can single-handedly thwart an…" another large rumble, more tentacles broke under the strain of having to hold up the mass. The Doctor continued as one by one they snapped. "…An entire, uh, alien invasion. All on her own. And that's you. So, just-"

"GET OUT OF THE WAY!" An electric blue flash of light momentarily blinded the Doctor, and an almighty force knocked both her and Clara backwards towards the tunnel mouth. The heart was finally no longer able to sustain itself; it went tumbling as all the remaining, tenuous roots broke at once. In front of them a large piece of the collapsing ceiling landed at the edge of the ledge, right where they had been kneeling a second ago. Clara was unconscious, slumped against the Doctor's shoulder, while the last line of defence between them and the dying trees was none other than the Lightning Girl.

"Nice of you to show up!" the Doctor said loudly over the cacophony around them.

"Forgive me for being intrigued by sudden reports of killer trees in Brighton," Esther argued, "What the heck is going on here!?" The Doctor didn't reply, instead observing the chaos. The heart crashed into the base of its chamber, rendered an amorphic mess of pulp. It was dead on impact, and with it the swarms of animated roots blackened and wilted. The attack ended, the rumbling quelled, and luckily the cave they were in managed to stop itself from collapsing. The Doctor's attention returned to her wife.

"Clara? Are you okay?" she lifted Clara's head, but Clara's eyes were closed and her face was covered in blood from her own nosebleed. The Doctor took a deep breath and placed her fingers on Clara's neck to check for a pulse. Luckily, there was one there. Weak, but detectable. "I told you you'd give yourself another aneurysm…" she said quietly, holding Clara's unconscious form in her arms. "Maybe I was too supportive…"

"Seriously," Esther reiterated, pacing in front of her. "You should have called me if there was something like this going on. Instead, I get a text from Mattie seeing if I could come and help out! You know I always have time to help you guys out, you're family."

"We managed," said the Doctor, "Sort of. And you were busy, you're supposed to be in San Francisco, dealing with some other earthquake."

"It's mainly just handing out water and blankets," she explained. The Doctor had never actually seen the Lightning Girl in person – well, not in her costume, that was; Esther did still visit them, when she took a break from her vigilante duties. It was, of course, of Oswin's design, skin-tight, bulletproof spandex, a flame-retardant cape with hood and a very fancy mask; it was all glass and had digital, blue images on it, dancing shapes. Probably full of all sorts of gadgets as well as battery reserves to make sure Esther never ran out of her famous lightning.

"Who are you supposed to be? Robot Rorschach?"

"I mean, kind of. Rorschach-slash-Spoiler. Slash Quarian. Had to give Os a lot of reference images… are you going to tell me what's going on? Explain why you're living the plot of Devil May Cry 5?" Esther's voice was being altered by a modulator in the mask she was wearing, but her accent remained plainly discernible. She was still plenty recognisable to the people who actually knew her.

"The fast version is that tiny seeds landed here in a meteor shower a week ago, and they've been down here growing into that thing Clara just destroyed all this time. They're alien trees that survive by drinking blood and the tunnels are filled with roughly two-thousand kidnapped but, thankfully, still alive victims. We only found out about this whole thing a few hours ago, the trees sprang up practically overnight. And we've been busy – Mattie's first week of school."

"Oh, really? How is she?"

"She's okay, I think. Apart from, you know, the threat of carnivorous, blood-sucking trees." Clara made an unintelligible noise and enveloped the Doctor's attention again. "It's okay, Coo, I'm right here, you're safe. The Lightning Girl came to rescue us."

"You were almost crushed," Esther argued, "By that big, falling boulder."

"She was phasing us," said the Doctor, stroking Clara's hair.

"Is it over?"

"It should be. She disconnected the heart and killed it. Although…"

"What?"

"You don't happen to have a crack-team of emergency landscapers on speed-dial, do you? Not sure who's going to clean up this mess."

"No, I don't. But I think you two should get out of here, before-"

"GO, GO, GO!"

A swarm of black-clad, red-beret-wearing soldiers came pouring out of the tunnel onto the really very narrow ledge, half a dozen of them armed with flamethrowers. Esther flitted out of their way, doing her borderline-teleporting, travel-at-lightspeed thing. It was UNIT, of course.

"You guys are right on time," said the Doctor, "By which I mean, late. As usual. You can point those guns somewhere else, too." She began to get to her feet, lifting Clara with her, who was woozy but just about regaining consciousness. Esther, still fully disguised, came to help her.

"Identify yourself," one of the soldiers asked. They were all wearing masks with breathing apparatus attached, leaving her with no way to easily discern between them.

"Me? I'm the Doctor. And I'm sure you're all familiar with the Lightning Girl."

"Ma'am, we have a Code Doctor and a Code Bolt. The immediate alien threat has been neutralised," the same soldier said into a headset.

"Code Bolt? Is that me?" asked Esther.

"Why am I just 'Code Doctor'? You know, you've always been very unimaginative. I always said that – especially about the Greyhound thing. Greyhound One, Greyhound Two, Greyhound Six." Clara made another noise. "Who'd you call on your radio? The new Greyhound One? We were just wondering who was calling the shots." A newcomer approached from the tunnel. "And whaddaya know, it's…" But she couldn't even take the time to think of something smart, she was overcome with shock. A girl had just entered, relatively young, perhaps only thirty. This girl was wearing thick-framed glasses, a multicoloured scarf, cricketing whites, a bowtie, and a tweed jacket. The soldiers all lowered their weapons and stood to attention.

"Oh. My. God."

"Wow," said the Doctor, "It's like looking in a… not quite a mirror, but… it's like looking at something, that's for sure…"

"You're the Doctor!"

"Correct."

"You regenerated."

"A long time ago."

"Into a girl."

"That would appear to be the case."

"An American!"

"Unfortunately. And you would be…?"

"I'm your biggest fan!"

"I'm flattered, truly…"

"And I'm Osgood."

"You're… wait, what? Osgood?"

"Oswin…" Clara mumbled.

"No, she said Os-good," Esther corrected.

"Petronella Osgood. I'm sure we've met!" she said buoyantly, "Ages ago. Fifty years, maybe."

"Hold on, but – but you don't look like – that's your real name? And you're in charge? Of these clowns?" she nodded at the soldiers.

"I used to work with Kate Stewart, tinkering."

"Huh. And, how old are you, exactly?"

"Older than I look."

"So's everyone else I know… What's your deal? What's your thing?" the Doctor questioned, very suspicious.

"That's right!" Esther exclaimed, "I knew I recognised that name. I've heard Ravenwood talk about her. Not this her, I'm sure, but a version of her in another universe. Something to do with Zygons."

"Zygons?" frowned the Doctor, then turned back to 'Osgood', "Do you know any Zygons?"

"I know of Zygons. I've never met any."

"We really need to confer more closely about the parallel universes," the Doctor added aside to Esther, who nodded in agreement. "So, you were Kate's PA?"

"A long time ago," she said, "And then I met Splodge." She rolled up her sleeve and revealed something the Doctor had not seen for a very long time, a creature wrapped around her forearm and latched onto her skin. It was like she was covered in blue slime that was half fused to her limb, but the Doctor knew exactly what it was.

"That's a Scek," she said, "You need to get that thing removed, they'll alter your biology in completely unpredictable ways."

"Splodge is my friend."

"A Scek? You're friends with a Scek? It's a parasite," the Doctor persisted, "You should not have let it attach itself to you, those things are like barnacles, they're almost impossible to get rid of. In fact, they have a habit of poisoning their hosts if they try to remove them."

"I wouldn't remove Splodge, he's like, my companion. Like you have companions."

"Yeah, it's literally nothing like that. But, sure, if you want to gamble away your life in exchange for eternal youth and dominance over a paramilitary group, then who am I to criticise?" The Doctor wholly disapproved of Osgood using a bond with a Scek to keep herself alive. They were known to force their hosts to do all kinds of unsavoury things in the promise of 'gifts,' gifts which were generally biological mutations much more harmful than just immortality. Like growing extra organs where there shouldn't be extra organs. The Doctor had once seen a Scek host die of a heart attack because the Scek grew them five additional hearts and their cardiovascular system imploded. And to put someone like that in charge of UNIT?

"I have tattoos of you."

"You what?"

"Who has a tattoo?" Clara mumbled.

"Just of your face. Not this face, your old faces," Osgood 'explained.'

"I've never felt so simpatico with Britney than at this very moment," said the Doctor, haunted by the idea of someone she'd never met having tattoos of her face.

"And I thought some of the things I read in my Twitter mentions were weird," Esther joked.

"We've met before," Osgood addressed Esther now, "Years ago. Before you were… you know."

"Excuse me?"

"When you were in UNIT custody."

"Those records don't exist anymore," said Esther firmly, though the Doctor could sense she was worried.

"But my memories do. What's your name? Ethel?"

"Yes," she lied, "And I guess your friend there makes you Eddie Brock."

"Makes me who?" Osgood asked.

"Eddie Brock. Y'know, Venom."

"Oh. I'm not into comics. They're kind of uncool."

"Enough about Sparky," the Doctor interjected before Esther went on a tirade how comic books were anything but uncool (which she had definitely been about to do), "We've sorted the tree problem now, you have my wife to thank for that-"

"You're married?" Osgood asked, sounding slightly disappointed. At least her not knowing who Clara was meant that Clara had been right earlier when she said Oswin had deleted all trace of them from UNIT's database.

"Yes. You could make yourself useful by rescuing all the people trapped in the walls out there. Should be about two-thousand, give or take. Start cleaning up this mess and getting them back home."

"Okay!" she said brightly, then turned to the soldiers, "The Doctor gave you an order."

"What? No, I didn't – I wouldn't give anybody an – oh, they're saluting…" she was dismayed to be saluted. "Could you let us leave first? We have somebody in the tunnels we need to grab."

"The glowstick boy?" Osgood asked.

"Yeah. The glowstick boy. I need to get my wife back to the TARDIS," she said, not wanting UNIT and their super-fan leader to get wind that she was living in Brighton; the last thing she needed was house calls from them. The soldiers stepped aside to allow the Doctor and Esther, carrying Clara between them, to leave through the narrow passages. It was going to be a very tight squeeze, so she hoped Clara would wake up soon. "It was nice to meet you," she told Osgood awkwardly. Osgood went bright red and made a strange noise. "Make sure these people are safe, or you'll have me to deal with. And that's not a good thing."

"Of course they'll be safe with us, we're UNIT."

"Yeah. Sure. I'll see you around, Petronella."

"She said my name!" Osgood exclaimed to the nearest soldier.

"Very good, ma'am," said the soldier curtly.

"Come on, Ethel," the Doctor lowered her voice, entering the tunnel, "Let's get out of here. And keep your eyes open for a husky and a pair of cats."