From the secretive way that Jessica is rubbing her eyes, like a child who doesn't want to be sent to bed, the Doctor might assume that it's been about a day since he went to fetch her. Her final university exams had just ended, and it had been his solemn promise to distract her with all the usual mystery and adventure and universe-spanning wonder and awe (her painstakingly chosen words, not his) until the day of the results. Then again, for a first day out, he might have overdone it.

The paramedics, by the way, are all still standing about. The young out-of-date man is still lying flat on the rubble, with Lizzie hanging over him. Jessica is away at the bag again, maybe looking for another clue, maybe just looking for-

"Ah!" she mutters with joy, and when the Doctor looks over his shoulder she is unwrapping a peanut-butter sandwich out of clingflim.

He looks away, pressing one hand to his suddenly delicate stomach. "That's eighty-three years old!"

"Is looking and smells fine."

"In that case don't eat the evidence."

She sighs and wraps it up again, puts it back in the bag.

But what the Doctor would mean to say, were he saying all of this out loud, is that all of this is going on around him. He himself is still part of the scene and part of the looking and arguing and discussing. But he's an old and very intelligent being, with both the prowess and the practice to be able to hold a small recap of the day's events.

It all started out very easy going. He got that right. Dropped the Tardis outside Jessica's exam hall, presented her with a box of Jammie Dodgers and explained the rules of proposition bets. And then off to a Swiss hillside to visit his dear old mate Julie Andrews on one of her old sets. Then a hasty hop to a film editing suite to remove themselves from the finished product. The Sound of Music could have easily become a very different film without that little bit of subterfuge.

Maybe they should have stopped for a while, after that. Had chips somewhere. Let his little peacekeeper, all studied out, fall asleep still humming Edelweiss to herself.

But, no, no, oh no, not him, nope, never crossed his mind to stop.

"Oi," and now that he's thinking about it he did have to nudge her to get her to listen, "Oi."

"Yes-what, Doctor?"

"I've got an idea that might go wrong, but if it goes right it might turn into a nice surprise for you."

Magic word, that. 'Surprise'. You can keep abracadabra and alakazam and keep open sesame and expelli-blooming-armus, you can keep them all. What spell is there that holds more power over the unsuspecting human than the simple word 'surprise'?

"Surprise for Jessica?"

"Yes."

"Is to be being nice surprise, if becoming surprise?"

"I wouldn't do it if it was nasty. But we might have to fight off some forest monsters."

She rolled her eyes, "Like her am being any scared of forrymonsters."

"And possibly save a damsel, but then, out of all the humans, we'll meet someone who turns out of be a very special creature."

"Like Mrs Vastra?"

"Same only different. If I've got it right."

She considered that. Tossed it up and warily concluded, "Doctor am much many times am right. Special creature am to be being surprise?"

That word again. Nobody can hear that word and not latch on to it, not pursue it. Matter of fact, the Doctor might almost say it was his favourite word, were it not for the existence of 'flibbertigibbet' in the human tongues, and 'rusk', precisely because it has been so much fun to pursue. In all the brightest moments of his life he has been pursuing surprise, rarely even knowing where to begin, only that the pursuit was going to be a blast. ('Surprise', in a side note, while he's noticing it, is almost an anagram of 'pursuit', making it really a very clever word indeed.)

And now, for instance, surprise!, a perfectly preserved, still-living human from eighty-odd years previous lying in a pit in the ground, lunch and newspaper intact. Surprise!

This, of course, neatly skips over the whole part where they rescued Lizzie from burning and the Doctor began to wake her up to her full potential, but that's all still very fresh in his head. Anyway, he decided round about the forrymonsters that this all probably could have waited for tomorrow. Oh well. It's all done now. Just this latest chapter to deal with. It'll be good practice for Lizzie.

The paramedics have started talking about the emergency drones coming in to lift them and the body up out of the crater. Jessica is happily reading the horoscopes from 2013, despite having no idea when her birthday is therefore what starsign would apply to her. So the Doctor kneels down by his rescued witch, her hair still smelling faintly of damp forest and hot torch, and asks her, "What is your diagnosis?"

"You're the Doctor."

"I am. And as such I am really very clever. Most of the time. There are a few dodgy moments, but mostly it's cleverness. And you are a million-billion-trillion times cleverer than me, Elizabeth, even if you don't know it yet. You'll get there, one zero at a time. How many zeros would that be, by the way?"

"Depends if you use American or English notation and if you really mean one sextillion. Either twenty-one or thirty-six."

"And a clever woman like you can't even give me a guess what might be wrong with this sadly-unfashionable soul here before us?"

"Soul," she murmurs back at him. She animates, getting caught up in her explanation, and the Doctor begins to smile, "That might be it. Or some part of it anyway. Doctor, the only real sense I get from this body is that, while it might be alive, there is certainly no one living in it. At best, it's an empty shell. At worst it is a fit dwelling for demons. Had this man a pact with the devil, and the devil come to collect? But then why does the body still live? And why has it not aged and withered?"

Well, they could pass a happy and exciting couple of days popping back and forth between 2013 and 2086 and trying to find out, but that sounds time-consuming and exhausting, and the sort of heavy-handed mystery he'd been hoping to avoid on this little jaunt.

He takes her by the wrist and guides her hand towards the body. Lizzie's arm stiffens, fighting him, and she sighs with relief when the female medic catches sight of them and cries, "Hey! We still don't know what's wrong with him. Don't make me order a quarantine."

Jessica climbs heavily up from where she's sitting. Pushes back her left sleeve. There is a round, bluish scar, like a knot in wood, on her forearm below the elbow. Out of this, slow and controlled, pushes a long, sharp stake, growing organically from her. Still in his grip, the Doctor feels Lizzie start to shake. "Don't worry about that. We'll do her later, once you've had a bit of practice with this man here, alright?"

"Can does what wants, mate," Jessica is growling, and moving with ease and precision across the broken ground.

"Easy," says the one called Nate, "Kelly here just loves ordering quarantines, don't you?"

In fear and shock, Kelly nods along until Jessica walks away again. Then, behind her back, hisses at him, "Didn't I apologize for the plague scare?"

"Four months in isolation-" he snaps, and they go back to arguing, the bio-engineered sword apparently forgotten.

Jessica snaps it off her arm and sits down cross-legged by the body. Holding the stake across her lap where Lizzie can quite happily stare blankly at it. "How are you feeling?" the Doctor asks gingerly.

"Fine."

"Only you were looking a bit grumpy and threatening on it there, and-"

"Doctor, can hear hovery-whirly noises, coming close. Is bad?"

"The emergency drones," he says, "coming to lift away the body. C'mon, Liz, give it a go."

Jessica is playing with the stake, balancing it on one finger by the broken end. She was so very quick to jump to his defence. Lizzie isn't sure if it's fear or trust that makes her put her hand back out and lay it across the mystery victim's heart.

It's like fire. Not big or bold, but strong against an overwhelming darkness. Like the flame of a candle. It burns right at the core of his being, and is irremovable, inextinguishable, despite everything else having been stripped away around it. There is no person here, she was right about that, but here in this spark is the person that longs to be, some scrap that even bleakest evil could not touch. Here is humanity striving to remain where all humanity ought to be impossible.

Lizzie lashes her hand away, hissing. The Doctor takes it, carefully studying the shiny round burn on her palm.

He asks what she saw, what she felt, and Lizzie can only stammer. So he takes her under his arm, nods to Jessica, "Find us a way back up the side. We'll meet this fellow again in his hospital bed." He lifts his voice, shouting to the medics over the noise of the approaching drones, "Where will he be taken, by the way?"

In the same moment that Kelly begins 'We are not at liberty to-', the unnamed third shouts back, "Obama Memorial," and receives a sound thumping from her for his troubles.

"Thank you. Now, as for us, back to the Tardis, I think. We all could do with a sound rest."

Three jumps ahead, marking her path with scratches of the stake, Jessica calls back, "Is not being much-very tired."

"No, you just threatened medical professionals at blade-point because they were naughty."

"Was helps him."

"Greatly appreciated, but isn't your pending degree supposed to be in Peace Studies?"

"Then not bothers helps anymore. And for Doctor information, strategically interventioning in conflict am being totally sound-"

"Don't even finish that sentence. Tell me you didn't write that on your exam paper."

She shakes her head and hops farther away from the conversation. "Honestly," he murmurs to Lizzie, "I really must find someone my own age to spend time with. The younger they get the more work they are."

"Was hearing that." Jessica crests the upper edge ahead of them. Stands looking at something in the distance, squinting against the oncoming night. "Doctor, what am means this?"

"Can't see it yet."

Jessica offers her arm and hauls him up with an ease Lizzie can't quite believe until she is given the same treatment. She might wonder, but the Doctor doesn't. Even if there were any surprise in it for him, he would be distracted. The beacon on top of the Tardis is flashing, a low double pulse like a heartbeat, or like the signal on a 21st century mobile phone that he has, "A message!" He begisn to run before he remembers to turn to them, "Do catch up, won't you, only I have a message, and I don't know what it says, and it's a message, and I have to go and see."

"And he complains of your childishness," Lizzie murmurs to Jessica.

"Heard that!" he cries over his shoulder.

Throwing open the door of the Tardis, the Doctor skids in, almost off his feet, falling forward onto the stairwell with his knee in his chest, but even the pain of that can't stop him, not until he swings himself around on a lever he's sure can take the weight and won't be irrevocably damage and comes to a screeching, clanking stop hanging on the monitor. His fingers waggle entirely of their own accord as they reach for the controls, looking at his latest message and where it's come from. He knows that address. It's Clara! Clara, and he wasn't expecting her, and she'll have something to say, and it will be – for those of you who hadn't guessed this already – a surprise.

"Messagemessagemessagemessagemessage-play!" And he pushes hard on the button.

"Doctor!" comes the terrified cry, and his excitement evanesces. There are two faces on screen and neither of them is Clara's. He doesn't even know how these faces were able to contact him, only that if they have, it must be dreadfully important. The crippling fear that crumples their features and hangs tears in their eyes is something of a giveaway too. "Doctor!" they're crying. Angie and Artie. Somehow here are two children, charges of his charge, pleading across eighty years, "Doctor, you have to help! Come and help, Clara didn't come home, you have to come and help!"

"Well," he mumbles, and sets a new course, "So much for the quiet night in."

The door closes automatically on Lizzie and Jessica before the Tardis can dematerialize.