December 24th 2013, Manchester, 9pm

The Doctor stepped out of his TARDIS and frowned. The air smelt funny. And not clown funny either; it was dank and musty and had a hint of rotten eggs. He straightened his bowtie and flicked his suspenders, stepping forward into the alleyway, Clara on his heels. She sniffed.

"Right, even I can smell that one. Was that you?"

"OH. Clara! No, it was like that when we got here."

"Whatever."

"Oh, shut up you. Odd though, isn't it?"

"Yeah, I suppose so. Kinda smells like… sulphur?"

The Doctor didn't reply, simply pulling out his sonic screwdriver and scanning the general area around them. It buzzed and began flashing ominously, sparking a worried face from Clara.

"Is it supposed to do that? I've never seen it do that before. Is it broken?"

"Of course it's not broken. But… that's impossible!" He smacked the device but the readings stayed the same, "Clara, the sonic is telling me that something impossible is happening. Which means that something very, very dangerous is about to occur."

"Right, so you're saying we have to leave?"

"That's exactly what I'm saying yes. We should leave. Absolutely."

They locked eyes. The Doctor grinned and immediately began walking away from the TARDIS and into the darkness, Clara falling into step beside him.

December 19th 2013, somewhere in the heart of America, lunchtime

Dean stretched. They'd been on the road for days, searching for a mystery, for something interesting. Sam had been staring at his phone for an hour.

"Sam, Garth will call if there's anything, but I'm pretty sure you can't will a problem into existence. Honestly, we should be glad when there's nothing to fight: less danger for the innocent bystanders." He didn't have any conviction in his voice though; he was just as bored and stressed as Sam.

Dean glanced in front of them. A small town with probably fifty people living in it was laid out in front of them in complete silence. He rolled his eyes and Sam looked over too.

"Burgers?" He pointed at a small joint at the end of the main road, checking his watch as he did so.

They locked the car and walked into the tiny bar. There were no waitresses to be seen, just one lonely bar tender, a cute smile on her face, her blonde hair falling into her eyes. When she saw them walk in, her eyes drifted over the two of them and noting Dean as the most enthusiastic to see her; beckoned him over. Sam sat down at a booth in the corner facing the window and checked out the menu.

"Uh, two beers and a Cheesy Biters Burger…" He glanced back at Sam, who raised his arm, "oh, sorry, two Cheesy Biters Burgers, please."

The girl nodded and wrote the orders down, fluttering her eyelashes as she disappeared out the back, probably to cook their meals.

"Man, check that out!" Dean nudged his brother, who nodded absent-mindedly and continued staring out the window.

"It's too quiet," Sam said, "not that it's always a bad thing, but, I dunno, something's weird about the silence, like something's going to happen."

Dean nodded, but he wasn't really listening, too busy staring at the girl who'd returned with their food and drink. He thanked her and she blew him a kiss as she went back to the kitchen.

Sam rubbed his eyes, tired from the long, intensely boring days. Dean tucked into his burger, when suddenly there was a whooshing sound, wheezing and stretching, and something blue began to fade into existence just outside the bar.

Both of them stood, knocking things off the table, running out the doors towards the materializing box.

"What the hell is that!?"

December 19th 2013, two hours later, 221B Baker St

Sherlock Holmes was bored. Not entirely unusual for him, but nothing had been happening. No interesting murders, no fascinating thefts, not even a brilliant plot twist on a soap opera. John was away with Mary and their daughter and wouldn't get back for another twenty minutes, so for the minutely foreseeable future, life would remain boring. Sherlock sighed.

"God, couldn't some criminals be even remotely interesting?" He stood and began pacing around the room.

Seventeen minutes later, John stepped through the doors and it was like he'd walked into a warzone. Books lay everywhere and pages were floating around the room. There were still those old photos and new clippings of that fascinating blue box there, but that was old news; probably some hoax, maybe even Derren Brown. He was surprised that Sherlock hadn't abandoned it yet. What he wasn't surprised about was the mess that the apartment was in, though he wasn't thoroughly impressed with it.

"Sherlock? I know you're bored, but really, you should be over trashing the place by now!"

He shuffled through to the kitchen and sat down on the closest chair that wasn't covered in what appeared to be chicken.

"Bloody experiments." He muttered.

Sherlock appeared from the other room and rubbed his forehead, looking decidedly happier than before, "how was your weekend away?" John opened his mouth to say something and Sherlock raised a hand, "don't, I know exactly how it was, and I know that I will find any stories you have to tell me very mediocre."

A wheezing noise began behind them but neither of them turned to look, John too busy being silently annoyed at his friend. Sherlock sighed in frustration.

"Oh, for heaven's sake, is there anything in the world even remotely interesting?"

"I could think of a thing or two." The Doctor stuck his head out of the TARDIS and John fell off his seat.

December 19th, a small town in America; in front of a bar, just after lunch

"It's a TARDIS." The tall man was wearing a bowtie and a tweed jacket, and unbelievably he was pulling it off, like no man should be able to.

"What?" Dean muttered; his eyes glued to the recently materialized blue box.

"This thing," The Doctor stroked it lovingly, "it's called a TARDIS. Time And Relative Dimension In Space. It's a spaceship."

Sam scoffed. "It's a Phone Box. A bit small to be a spaceship, don't you think?" He risked a sideways glance at Dean, who was regaining his composure and closing his mouth.

"Nah, it's bigger than it looks." Clara grinned, stepping out of the TARDIS.

"Oh, honestly, could you be any more dramatic? Would you like some backing music?" The Doctor rolled his eyes and nudged her. She straightened up and the smile dropped from her face.

"That's weird, Doctor, these two guys, they remind me of some books that I used to read. About two brothers and they had a car… an old one, a classic... what was it again?" She looked down the road and saw the Impala standing out like a large black car against a pale backdrop. Which was exactly was it was.

"Oh my god, it was that car! Are you guys Winchester impersonators?"

Sam and Dean exchanged looks and rolled their eyes.

"No lady, we're the real deal." He didn't expect the girl to believe them, which she didn't.

"You're joking right; two brothers fighting demons and monsters, driving round America in a classic Impala just waiting for something exciting to happen? It's a bit, unrealistic, don't you think?"

The Doctor looked crestfallen, "What do we do all day every day?" A rhetorical question, but one which drew interested looks from the Winchesters.

"That's a good point, who the hell are you?" Dean raised his voice, expecting them to shrink back and maybe jump into the ridiculous box. On the contrary, the Doctor stepped forward, extending his hand in greeting.

"I'm the Doctor, I'm a Timelord from the planet Gallifrey, I have two hearts, a sonic screwdriver and a cool bow tie, and we need your help. This is my companion Clara; gorgeous, clever, slightly annoying sometimes and she is my impossible girl. You must be the Winchesters. I've been looking all over for you."

Clara laughed and then, when she saw that the Doctor was not, in fact, joking, she pulled him aside.

"Doctor, you're joking right? The Winchesters aren't real. They're just characters in an overdramatic book series."

"Hey, who're you calling overdramatic? That stuff all happened, so you can get your pretty little panties out of that twist they're clearly in. Besides, what's more dramatic than a randomly appearing blue box?" Dean argued and Sam put a hand on his chest to stop him stepping forward.

"Good point." Clara conceded, "But… If you're real, that means all that stuff you did in those books was real which means that you've stopped the apocalypse, more than once. That's brilliant!"

"Thanks," Sam smiled, and Dean puffed out his chest in pride.

"Of course, you'll never have saved it as many times as us, and especially not the Doctor, but you've done pretty well so far. Don't be put out or anything, but saving the world is kind of our day job." Clara added, and Dean deflated. Sam stuttered and frowned, but the Doctor was more interested in his own agenda.

"So, Winchesters. I have a job for you, if you want one."

"What does this job involve?" Sam asked sceptically. The Doctor just smiled a mysterious smile and Dean caught sight of how old his eyes were. Those old eyes looked at the brothers and they sparkled with adventure.

"Lots of running."

December 19th 2013, three hours later, 221B Baker St

Sherlock strode forward.

"How the hell did you get in here?"

"Trade secret. I could tell you, if you want, but that would defeat the purpose of the mystery, wouldn't it? Now, would you like something interesting to do or not?" The Doctor watched as Sherlock's face began to light up.

"Parlour tricks." Sherlock muttered scornfully, but the Doctor just shook his head. It was then that the Doctor noticed the photos and news-clippings of his TARDIS on the wall beside him. Watson stood and protested loudly, but Sherlock was already on a roll. He walked around the exterior of the TARDIS, talking to himself as he went.

"Can't have arrived via window or door, no way up without being noticed… must have… no, that's impossible… the technology is far too advanced… brilliant… absolutely not… oh of course."

"Well, Mr Holmes, have you come to any conclusions?" The Doctor asked, and Sherlock tilted his head.

"This is a spaceship, possibly one that travels in time, and you are not of this world."

"My goodness, you are as good as all the hearsay. And how do you figure this?"

"Well, there was no other way that you could have gotten in here other than materialization, because there's no clear pathway from the door, and we would have seen you come in. Though the ship is very small, probably just a one person vehicle, maybe a two person vehicle, it can travel very quickly and appear from nowhere, like a form of teleportation, so it's almost definitely from the future, yet the appearance it takes is from the 1950s or 60s, a London Police Box. A bit retro, don't you think? But proving my point that you a probably a time traveller, or just have really bad taste."

"Hey!" The Doctor protested.

"And as for you being alien, well that's obvious." He said with a flourish.

"It's not obvious to me, care to explain?" Watson growled.

"He's wearing a tweed jacket and a bow tie, what more do you want?" Sherlock replied bitingly, "Alright, apart from the ridiculous attire, which he manages to wear quite well, he's standing outside a piece of technology that is greatly advanced, which of course makes him advanced, but not many humans would want to give their ship the appearance of something so… old fashioned. Let alone that fact that he simply exudes power, which people just don't. But the real trick was the eyes."

"What about his eyes." John asked, stepping up to study them.

"Look at them John. Such old, ancient eyes, hidden in such a young face. No human's eyes are that old. Why you look human, though, is something I can't discern."

"Oi. You look Timelord, we were here first." The Doctor remarked, not for the first time in his life.

"Interesting. Timelords. Fascinating name. I'm guessing my time travel theory was correct, which means that you're here for a reason. What do you want?"

"Well, I'm partially here because I wanted to meet you Mr Holmes. You're something of a legend, but the main reason I arrived is because I have a mystery. A very fascinating mystery with a lot of things to solve. You in?"

Watson and Sherlock stepped forward, Watson albeit a little reluctantly.

"Of course. I wouldn't miss this for the world."

The interior of the TARDIS, time and space in a state of temporal flux

Dean sighed. "More people? Really, more?"

"Ah, yes, but these are special people. Ladies and Gentleman; Sherlock Holmes and Doctor John Watson."

The TARDIS erupted in sound, everyone protesting or laughing or glaring at each other. Clara choked on the cup of tea she held in her hand and Dean groaned in apprehension, taking the cup from the girl.

Sam blinked a few times and once he'd regained his composure he stretched out a hand to the two new arrivals.

"So you're Sherlock Holmes. Wow. I read all the books; big fan." He grinned, a little shocked. Sherlock and Watson were introduced to everyone before they all gathered around the central console. Watson seemed a bit sick and Clara went and stood next to him, like she had done with Dean when he'd first stepped on.

"Weird isn't it? Don't worry, most people get like this when they first get on. Although Sherlock seems to have taken it in his stride quite well."

Indeed Sherlock was wandering around the room, staring at nozzles and switches and glancing furtively, trying to take everything in with one gaze.

"Alright, enough of the showing off," Dean turned to the Doctor, "Why are we here? You promised a job, but right now all we're doing is picking up supposedly mythical characters from books written 150 years ago."

"You're one to talk, handsome fictional demon fighter." Clara responded.

"Handsome?" Dean asked, a smile creeping to the corners of his mouth.

"Oh… shut up." She glared, but she wasn't serious and they both knew it. He found himself greatly warming to the pretty brunette, and she looked away hurriedly so as not to catch his eye for too long.

The Doctor stood in front of his tiny army and held out his hands.

"Dean and Sam Winchester, the most famous hunters in the universe, and Sherlock Holmes and John Watson of course need no introduction. You've asked why you're here? Something impossible. Something impossible and fascinating and very, very bad has happened, and I need your help. You guys are my dream team! Isn't that exciting?"

Sherlock raised an eyebrow and Sam sat back in anticipation of what was to happen next. The Doctor twiddled some switches and room became dark, a screen flaring to life in the centre.

A demon stood at a crossroads at midnight, the only light cast by the moon. It was waiting for someone; this deal had been pre-arranged. Three minutes later, some walked up the north facing road. They were facing away from the camera, which was situated across from a closed convenience store. Words were exchanged, though there was no audio on the recording, and then the visitor turned and grabbed the demon, thrusting a knife into its belly and watched it writhe on the ground before walking off.

"So?" Sam said. "Probably just another hunter trying to get rid of a demon."

"Nope. See here's the thing. That recording was taken two nights ago, but according to the TARDIS, that particular exchange took place over 150 years ago. So how did that camera capture it? Because we've already been there and checked it out, and the readings are odd, but that's not even the impossible bit. Are you ready?"

The screen flickered to life again.

Sam, Dean, Sherlock, John, The Doctor, Clara, River and Castiel all stood on that same crossroads, Sam, Dean and Castiel grabbing stuff from the trunk of the Impala, Sherlock and John checking their guns and The Doctor whipping his sonic screwdriver around, scanning everything, waiting for something to spark. A demon appeared at the beginning of each road, three men and a woman. Behind them were the Silence, some Cybermen, and what seemed to be the head honcho, and man in a neat black suit, walking slowly behind the rest, a crazy grin on his face.

"Moriarty." Sherlock hissed; anger pasted across his face. Watson jumped forward and the Doctor put a hand on his arm.

"I know what he did to you. I know how much you despise him. But that's not Jim Moriarty. That's a demon possessing his body. And I'm sorry, but it's going to get a whole lot worse." The Doctor cringed.

"Worse? How could that possibly be worse?" Dean yelled. There was a rustling sound behind them and Castiel stepped into the room.

"A prophecy."

"Urgh, have I mentioned how much I hate those?" Dean spoke through his teeth, and Sam nodded.

"Eight noble men and women,

Fighting evil's cause,

Eight start the fight; only five remain,

When the evening has reached its pause.

One will die, one will fall,

One will escape this life,

The five remaining hold their breaths,

Until they've escaped all evil strife." Cas rolled his eyes, "I don't understand why prophecies have to rhyme. So mediocre. An angel crafted this prophecy, so it should have had more class at least, but she chose to keep it tacky."

"Haven't I always said angels are dicks?" Dean caught Castiel's eye. "Except you Cas. Although, sometimes…" He drifted off and Castiel glared, inducing a giggle from Clara. Dean winked and put one hand in the pocket of his jeans, both him and Sam having ditched the FBI suits. He was never surprised at how easily he drifted between the two, although he loved his casual demon fighting clothes much better.

His eyes flicked around the room, finally settling on Clara, and most prominently, her short black skirt, which showed off her long tanned legs. Dean coughed and averted his eyes, choosing to stare at one of the levers on the centre console instead of the gorgeous woman.

If Clara saw him looking, she didn't show it, just continued to stare straight ahead. Sherlock and the Doctor, however, glanced at each other knowingly and continued to discuss the prophecy.

"Falling. Haven't we had enough of falling." It wasn't a question. Sherlock scowled at the ground. "I need Molly, or Mary, or someone. Everyone in here is just… boring!" He began to pace and fidget, unable to keep still.