There is music blaring from the TARDIS speakers. They’re good speakers and it fills the room, although it isn’t quite loud enough to flutter the tinsel. To any passer by (nothing but Reapers on this occasion, seeing as this is the time vortex) the sight of a flying police box is already an unusual occurrence, never mind the strains of Merry Christmas Everybody that can be heard emanating from the inside.

Ryan taps his foot; Yas is nodding her head in time with Don Powell’s drums. On the far side of the room, Graham is looking through a battered cardboard box full of vinyl.

“’Ere, Doc,” he says. “Some of these look vintage, but they ain’t even come out yet!”

The Doctor doesn’t look round from where she is rigging an eight foot tall Christmas tree with fairy lights. “That’s what happens when you travel in time, Graham. It’s all relative. We’re like time-travelling vagrants with no fixed abode. No – ” and she jumps down from the tree, turns and crosses the room – “not vagrants. Hobos. That’s it. Cosmic hobos.”

“That’s got a ring to it,” says a clearly impressed Ryan.

The Doctor shrugs. “Made it up on the spot.”

“Hobos,” says Graham. “And maybe tomorrow, you’ll want to settle down?”

He grins at Yas and Ryan, both of whom are giving him blank looks. “Strewth,” says Graham, giving up. “I’m getting old.”

“Rubbish,” says the Doctor. “Now come on, we’ll have no soul-searching on Christmas Day. We’re gonna enjoy ourselves.”

“How can you be sure it’s Christmas, though?” asks Yas. “You just said time is relative.”

“Yeah,” chips in Ryan. “I mean for all we know it could be New Year’s Day.”

Another shrug. “Christmas Day, New Year’s Day; does it really matter?”

The console phone rings; the Doctor snatches the receiver from its cradle. “Hello? Yes? Really? Well, which accident are we talking about? I mean, I’ve had several hundred in the last – hello?”

She pulls a face. “They always ring off at that bit.”

“Listen,” says Graham. “Seeing as it is Christmas, can’t we… I dunno, do something?”

“What did you have in mind?” asks Yas.

“Well, we’ve got a time machine.” Graham gesticulates the time rotor and a console he doesn’t pretend to understand. “Can’t we go back and see it properly? You know, the first Christmas?”

The Doctor cranks a lever and the TARDIS biscuit dispenser shoots out a fig roll. The Doctor sniffs; they’re not her favourites, but waste not, want not.

“That’s an interesting idea, Graham,” she says, cramming it into her mouth and passing over a pen and paper. “I want you to write it down on this and then drop it into that box over there. The one next to the chair with the stuffed panda.”

Graham obliges. The container is dark brown, shoebox-sized and labelled THINGS WE’RE NOT TOUCHING WITH A BARGE POLE. As Graham lifts the flap, a loose piece of paper that hadn’t been fully posted drops to the floor; it is recovered by Yas.

“What’s that one say?” Ryan.

“’Anne Frank’,” replies Yas, nonplussed.

There is a clunk as the ship lands. “We’re here!” announces the Doctor cheerily.

“Where?” This is Graham.

“No idea,” admits the Doctor. “I turned on the randomiser. Set the date for Christmas Eve and left the rest to chance. Could be any planet in the universe.”

She punches buttons, and the screen displays an aerial view of Stoke-on-Trent.

“Oh well,” says the Doctor. “Maybe the pub’s open.”

***

The crew are getting their coats and hats when there is a knock at the TARDIS door. Everyone stops and looks awkwardly at one another, not sure what to do; it is like being in an office when the fire alarm goes off.

Yas is the first to act. “I’ll go.”

“Does that happen often?” asks Graham, indicating the door, which causes the Doctor to have several flashbacks at once and clap her hands to her head.

Outside the TARDIS is a Moses basket; there is a small baby inside, cooing up adorably at Yas, who feels a hundred unexpected motherly instincts suddenly kicking in like toothache.

She leans forward to pick up the baby and her head collides with the young woman who is leaning round the open door.

“Sorry, is this 23A?” she says.

Yas’s brow furrows. “No, it’s – ”

“Never mind.” The woman gathers up the Moses basket and is gone.

In many ways, Yas is relieved; it would have been one cliché after another.

***

The civic hall is warm and decently lit. The play is sold out but the Doctor has blagged their way in with the help of the psychic paper, with the poor family whose seats they have pinched conveniently forgotten so that people can complain about it on Twitter.

“It’s an absolute honour to have you here, Lady Hyacinth,” says the fawning mayoress as she shows them to their seats. “Thank you for coming to our humble production.”

“No problem,” says the Doctor. “I love the theatre at Christmas. I was at the first ever performance of A Christmas Carol. 1844, I think.”

The mayoress gives the Doctor a funny look, and the uncomfortable silence is broken by Graham. “She means the first in Staffordshire, don’t you Doc – I mean Your Ladyship?” and he rubs the sore spot where Yas has just elbowed him.

“1844? That’s an unusual start time.”

“The producer was Flemish,” says the Doctor, as if to explain things.

The four of them sit, two to a row, and Yas turns in her seat. “So why are we really here? Is this the part where you start telling us about artron energy or temporal readings?”

“No,” the Doctor admits. “I just really fancied seeing a nativity play. And, you know, that last pub really was a bit dead.”

“It cleared out when Elvis here started on the karaoke,” says Ryan.

Graham is having none of it. “I’m not making any apologies for enjoying meself. It’s not my fault they don’t appreciate good music in there.”

“Yeah, but The Millennium Prayer? I mean really?”

“Hush you two,” says the Doctor, as the lights dim.

***

It is an hour later. Graham is struggling with a singlet. It is coarse and itchy and extremely uncomfortable.

“Why do I have to be the blasted innkeeper?” he fumes. “Could have been a wise man, or even a shepherd. But no, I’m saddled with the worst costume of the lot!”

“Someone’s got to be the innkeeper,” says the Doctor, as she pulls the white tunic over her head. “We drew straws, remember? Besides, you’re the only one who actually looks old enough to run a pub.”

“Thanks very much,” says Graham, huffily.

Yas is pulling the splinters out of her shepherd’s crook. “I still don’t understand why all this is necessary.”

“I told you,” the Doctor reiterates. “There’s something very wrong with this production. It’s 2018. This script hasn’t been written yet. It’s not due to be written for another sixty years!”

“But it’s the nativity,” says Ryan, adjusting his cardboard crown. “There’s only so many ways you can tell that story, aren’t there? Couldn’t it just be really similar to the one you remember?”

“Not this one,” says the Doctor. “This one is unique. Even the songs are new. Someone is messing about with time, and the only way to work out who’s responsible is to get close to the director, and the best way to do that is – ”

“Wait ’til the show’s over and catch him backstage?”

There is a tumbleweed moment.

“No, says the Doctor, slightly abashed. “It’s to go undercover and ingratiate ourselves in the cast by performing the second half of the play, and wind up looking completely ridiculous in the process.”

“Oh well, that makes sense.”

Ryan agrees with his grandfather, although he’s not about to say so. “But why’s it such a big deal?”

“Because today it’s an anomalous nativity play. Tomorrow it’s world events. There’s only one person allowed to mess around with the timeline, and that’s me. Well, me and the people who travel with me. Sometimes. When I feel like it.”

The Doctor stretches the fabric of her costume so that it fits to the knees. “Right, now listen up. You all know your lines, thanks to the memory pills I gave you, so get out there and give it a hundred and ten per cent. Own the stage. And when you’re not on the stage, I want you back here, sneaking around for anything and anyone out of place. There’s something rotten in the state of Denmark, and we’ve got to find out what it is.”

She pops a tinselled halo onto her head. “Let’s go, team!”

They leave the green room, ignoring the muffled shouts and thumps from inside the locked cupboard.

***

Graham is shuffling offstage, having completed his first scene, which was to deliver blankets and fresh water to an unsuspecting Mary and Joseph. The uncomfortable silence that followed their apparent surprise at the cast change was thankfully misinterpreted as exhausted relief by the audience, and the scene went off without a hitch.

The Doctor has a hitch of her own, and is in the process of climbing into it, up in the gods. “I’ve not done this since the 1936 Walthamstow production of Peter Pan. That didn’t end well. Mind you, I was a bit heavier. And I had a scarf.”

Graham passes Yas the cuddly toy nestled in her armpit. “You ready?”

She sighs. “Do I really have to sing to a sheep?”

“Don’t worry,” says the Doctor from above. “You only get two verses before I interrupt.”

She peeps through a crack in the curtain at the audience. “Hang on. Is that – ”

But Yas has gone, and the sentence is left dangling, much like the Doctor herself.

***

Yas is only halfway through her second verse when the Doctor crashes through the gap in the curtains, does a floating somersault, gets her legs caught on the wire, and crashes unceremoniously to the floor of the stage.

Forgetting themselves, Graham and Ryan rush on from stage left. “Doctor! Are you – ”

“I’m fine,” mutters the Doctor, getting to her feet and brushing the straw from her costume. “But I’ve figured it out.” She adjusts her halo – it is now only slightly wonky – and tries to hide the tear in her costume.

“Ladies and gentlemen!” she shouts through the fourth wall. “Sorry to interrupt. I’m the Doctor, and I have to report that you’ve been watching something that shouldn’t actually exist yet.”

“What do you mean, shouldn’t exist?” cries someone from the audience.

“I mean it’s not been written yet.”

“Then how come we’re watching it?”

The Doctor makes to reply, but is interrupted by an angry figure dressed in black who has barged up from the front row.

“Curse you!” he cries. “You have ruined my play.”

“Your play,” says the Doctor, angrily, “is early. Far too early.”

“All I wanted was to stage a simple nativity. Make a bit of money. Buy a small house to settle down with Mrs Vivanche – ”

“Hang on,” says the Doctor. “You’re Sebastian Vivanche? The time-travelling theatre director?”

“Yes! The one and only, for the little it’s worth. I mean, I don’t want much. I just hop around from century to century and put on a play here and there. Nothing drastic. Here’s me thinking 2418 would be quiet.”

“Sorry, did you say ‘2418’?”

Sebastian blinks. “Yes.”

“You’re four hundred years early.”

A light dawns in the director’s eyes. “That explains the food.”

“I told you we should have bought a programme,” says Graham.

“They were a fiver!” the Doctor protests. “I’m not paying a fiver for a cast list and twenty-six pages of ads.”

Ryan blinks. “So basically there’s no plot to take over the world? No evil mastermind? This has all been a colossal misunderstanding?”

Yas prods him playfully. “You ought to be used to that by now.”

“Not quite.” The Doctor has left the stage and is striding, insofar as her costume will allow, across the packed civic hall past the captive audience, most of whom are too stunned to say or do anything. She has reached an oddly-dressed couple in their late thirties and a ten-year-old girl who appears to be their daughter. Unlike the rest of the audience their expressions are of bored indifference, rather than incredulous silence.

“I wondered when we’d meet again,” says the Doctor. “You almost beat me at Ragnarok, and then I thought I’d beaten you. Is this your doing, this play-out-of-time?”

The man stares at her as if she were something he’d found on the bottom of his shoe. “I beg your pardon?”

“Oh, come on.” The Doctor is clearly enjoying this Poirot-like unmasking. “You think a change of clothes is enough to get past me? You think I don’t remember your antics at the Psychic Circus?”

The oddly-dressed man is the living embodiment of haughtiness. “I assure you, young lady, I don’t have the slightest idea what you’re blathering about. And for that matter, neither does anyone else.”

“Maybe not,” says the Doctor. “But let’s see how they react when I show them who you really are – ”

She pulls at his ear, hard, in attempt to rip the mask from the front of his face. It is not working. The Doctor tugs and stretches, ignoring the screaming. “Come on, come on, why won’t you – ”

“Doctor?” Ryan and the others have joined her. “I don’t think that’s a mask.”

“OW! Ow, ow, ow! That really hurts!” The Doctor has let go and the disgruntled theatregoer is rubbing his ear, which seems to be longer.

The Doctor strokes her chin. “I was so sure they were prosthetic.”

“That’s enough!” says a voice like thunder: it is the councillor, striding over to the disgruntled family group. “I’m so sorry, Chief Constable.”

“Ah.” The Doctor looks as sheepish as the lamb that Yas was holding. “Yeah. Sorry. Mistaken identity.”

“Doctor?” Graham is looking around at the crowd, most of whom seem to be rising from their seats and advancing on them. “I think we ought to be making a move.”

“Good thought.” The Doctor surveys the angry mob for possible exit points. “Right, everyone with me. When I say – oh, never mind. Run!”

They duck through the crowd and are at the fire doors when the Doctor runs back to Sebastian, sitting dejected at the side of the stage.

“Could I have your autograph?” she asks, thrusting a pad and pencil under his nose. “Big fan.”

***

It is later. The TARDIS crew have cleaned their wounds and changed their clothes, and the alcohol that wasn’t used to bathe cuts and scrapes is now in the process of being drunk.

“The thing is, fam,” says the Doctor in a manner that will never not be awkward, “I don’t understand why you’d spend Christmas with me, instead of your own families.”

“We don’t really do Christmas,” says Yas.

“And Ryan’s about the only family I’ve got,” says Graham, to which Ryan nods in agreement.

“Oh,” says the Doctor, who’d rather been hoping for something a little more heartfelt.

“So those people you thought you recognised,” says Yas, anxious to change the subject. “You’ve met them before?”

“Yes. Well, no. I don’t know.” The Doctor is morose. “It looked like them. They were the gods of Ragnarok.” She sighs. “D’you know, sometimes I miss being Scottish. Time was that’d just roll off the tongue.”

There is a slightly gloomy silence. All of a sudden, Ryan pricks up his ears.

“Can anyone hear sleigh bells?”

The sky outside the TARDIS is a cloudless ebony encrusted with the pinpricks of stars. A cold moon shines down across the distant hills. But it is what is in front of the moon that has them staring: a miniature sledge, pulled by eight tiny reindeer.

The group watch it go by, and find their mood lifting just a little.

“It’s so small,” notes Ryan.

“No,” says the Doctor, her eyes shimmering faintly. “It’s just far away.”

She waves up at the sledge. “Merry Christmas, Jeff!”

And, from far away, they’re sure they can hear a distant voice crying “And to you, Doctor!”

Yas gives the Doctor a look. “Jeff?”

The Doctor returns the look with one of her enigmatic smiles. “Ah, well. That’s another story.”

And they all go back inside the TARDIS so that she can tell it.

With very special thanks to Christian Cawley.