22nd December 1929

A piercing whistle split the air in the otherwise quiet rustic countryside. A thin crust of snow covered the fields, as well as the distant, rolling hills. As the ground began to tremble, a small hare looked up sharply, and bounded away.

A beast of a locomotive hurtled past, belching a great cloud of black steam.

A brilliant flash of apple green! Trailing behind, two score carriages, painted cream, auburn, midnight blue.

Within a minute, it was gone. The snowy countryside was still once more. The land branded by the iron tracks was the only indication of civilisation.

However, the landscape was all well and good: scenic, quaint, almost – but by no means remarkable. The train, on the other hand…

There were two interesting things about this train, travelling non-stop from London to Edinburgh at 90 miles per hour.

First: it was the most famous train in history, the engine preserved for centuries along with its name and number; lovingly restored, in minute detail, by passionate, extraordinary people – people who dreamt of keeping the memory of the age of steam alive.

Second: an ancient artefact – from another world – was on board the train at this particular moment. It was an object highly sought after. Legend told that it wielded great power. Power, so great, that if it were to fall into the wrong hands… bad stuff would probably happen.

Third – yes, third: there could only be one thing that linked the first and second things together. Well, one person. The Doctor.

"Get out of the way!" the Doctor yelled, charging along a carriage, about halfway down the train.

The carriage jolted sharply, and the Doctor's arms flailed, as he almost lost his balance navigating the narrow, bustling corridor.

He risked a glance behind him, to check if he was still being followed. Inevitably, he was. Those guys weren't about to give up the chase without obtaining their prize.

The Doctor wrestled his way through a doorway, locking it behind him with the sonic screwdriver. Not that that would stop them. It hadn't on the previous fourteen doors. His pursuers merely smashed through them, or blasted the locks with energy weapons. However, the Doctor was a little sentimental, and he wouldn't want the sonic screwdriver to feel left out.

Ignoring the bemused looks people gave him as he dashed through the compartment, the Doctor patted his pocket, in a hearts-stopping moment of panic.

Surely, he hadn't lost the most dangerous relic in his possession – the same relic that a bunch of rather angry mercenaries were after.

No – it was still there, the Doctor realised, with an exasperated sigh of relief. He pulled it out of the pocket of his velvet jacket, just to make sure.

It was a metal disc – no bigger than a coaster. The thing was intricately engraved, not unlike the patterns of a snowflake – and probably just as unique. Certainly, the Doctor had never stumbled across an object like it. Not knowingly, anyway.

He slipped it back into his pocket, and picked up the pace again. Judging by the splintering of wood, and the terrified screams of the human passengers, they were not far behind.

The train rocked side to side, throwing the Doctor against the cold window pane, which gave him a moment to notice that the English countryside had fallen away, and they were now passing over a viaduct.

Lovely as it was, now was not the time to enjoy the view. The Doctor continued through the compartments, sidling past people wandering along the narrow corridor. He attempted to blend in, mainly by apologising to them as he pushed them out of his way.

It took the Doctor ten minutes to reach the coal tender at the head of the train, and a further five to argue with the engine driver and the fireman about what he was doing there. They weren't convinced by his bluff, even with a pass issued by the LNER, forged by the psychic paper. However, they didn't notice the Doctor slip the metal disc in amongst the coals, piled up ready to be shovelled into the furnace.

It was a risky move, the Doctor admitted, but it was highly unlikely to sustain any damage at such a low temperature. This thing had clearly been designed to withstand far greater pressures. At any rate, seeing the object destroyed would be better than seeing it fall into the hands of the pursuing mercenaries.

The Doctor apologised profusely, and retreated out of the engine compartment, under the dark glares of the drivers.

As he raced back through the first class carriages, he very nearly ran straight into his pursuers.

"Oh, excuse me, gentlemen."

He examined the figures up and down. There were about six of them: stony, grey-skinned humanoids, clad in rusting steel armour, tainted with dents and scratches. Thick black cables snaked from the armour, piercing each mercenary's neck. The Doctor quickly deduced that these cables supplied the mercenaries with vital nutrients, and that the armour was not actually armour.

They were cyborgs – part organic, part machine. A conclusion fully supported by the evidence that one of the mercenaries had a bionic eye, bolted to its flesh.

The leader of the mercenaries raised a four-foot long metal pipe – actually a deadly energy weapon - to the Doctor's nose.

The Doctor straightened himself up, and raised his eyebrows innocently.

"You will be decimated," the leader growled, in a rasping tone. It was a noise that wouldn't have sounded out of place in a steelworks factory.

The Doctor frowned, peering at the cyborgs in a befuddled manner.

"You do realise that means you'll only destroy one-tenth of me?"

A couple of the cyborgs shared querying looks, attempting to process the Doctor's logic. The leader, however, kept its weapon squarely aimed at him.

"It is not relevant. The end result will be your termination."

"Ah…" muttered the Doctor, feigning an expression of disappointment. "That'll be a shame. I've always wanted to go and visit the Sky Mountains of the Altruistic Oasis. I'll never have the chance, now," he spoke forlornly.

"Enough of your verbalisation," the leader barked, "Where is it?"

The Doctor looked around him, pretending not to follow. He saw the faces of two dozen confused and intimidated passengers, frozen with fear.

"Where is what?" he asked.

"The Matrix," the cyborg thundered.

The Doctor checked his watch.

"I think you'll have to wait about, ooh… seventy years for that."

"Hand us the artefact!" grunted a second cyborg, raising its – slightly smaller – weapon.

"Or we will start eliminating them." The cyborg swung a gauntleted fist in a wide arc, indicating a group of passengers.

"Oh! That artefact," the Doctor relented, slapping his forehead as though he'd suddenly remembered. "I don't have it."

"You stole the artefact from the Tranquil Archives precisely twelve seconds before we stormed the complex," the leader grunted.

"I'll take that as a compliment on my impeccable timing," the Doctor conceded. "But I still don't have it."

"Then you have entrusted it to one of the humans?" the mercenary speculated. "It would correspond with your characteristic practices."

"My, isn't your vocabulary impressive?" the Doctor mocked.

"We will interrogate every individual on this vessel," the leader ordered. "Destroy them if they do not comply."

"That won't be necessary," the Doctor interrupted, leaping between the leader's weapon, and the trembling passenger it was aiming at. "None of them have the artefact."

"But it is aboard this vessel. We will find it without your assistance. Terminate the humans who stand in our way."

"No," interjected the Doctor, "I've hidden it. You will never find it. At least, not without my help."

The leader lowered its weapon, and stomped towards the Doctor – black, steel-capped boots hammering the carpeted floor. It swiftly raised its gauntlet, and grasped the Doctor's throat.

"You will divulge the location of the artefact, or these humans will be tortured," the leader rasped. "It is a known weakness of yours – which we will not hesitate to exploit."

The Doctor grimaced.

"You won't be able to find the artefact unless I'm still alive," he gasped, "And if you hurt any of these people, I won't help you."

He held the leader's steely gaze for a moment, until he was released.

The Doctor sucked in a lungful of the smoke-filled air, massaging his throat.

"You are indeed a conscientious opponent, Doctor," the leader growled.

The Doctor inclined his head.

"I don't think that meant what you think it meant."

"The language has not been assimilated correctly," the cyborg acknowledged. "Show us the artefact, and in return, we will show benevolence."

"Very well," the Doctor agreed. "But do not think that you can find a weakness in me. You have no idea what I am capable of."

"You will not attempt to mislead us, Doctor," the mercenary warned.

The Doctor whipped out the sonic screwdriver, wielding it like a beacon ahead of him.

"How did you get here?" he challenged. "Was it a… primitive teleport by any chance? One such as this?"

The cyborg leader's eyes widened, and it barked an order to the other mercenaries.

"Decimate the humans!"

The Doctor flicked on the sonic screwdriver, and it issued an exorbitantly loud buzz, that seemed to distort the very air around them.

The cyborgs shimmered, and vanished, switched off like an old computer screen, before they could fire a single shot.

The Doctor ground his teeth angrily.

"Reversed the polarity, and disabled their teleportation technology," he announced. "They won't be back."

A round of applause echoed all around him. The Doctor was astonished. Did they think this was all some kind of in-flight entertainment?

Nevertheless, the Doctor bowed curtly, presenting the bemused passengers with a wide grin, and offering his thanks.

He quickly saluted them, before making his way back through the train, to the buffet lounge. After all this exertion, he was craving a snack.

He ordered a fish finger butty from the mystified waiter, and took a seat, opposite a little girl with pigtails. She looked bored.

The Doctor opened up his sandwich, and began adding a selection of jelly babies to the dish.

He noticed the girl studying him in confusion, and offered her a jelly baby.

It seemed to diffuse the tension, and she spoke:

"Were you the man who was being chased by those mechanical men?"

"That's right," the Doctor replied enthusiastically, through a mouthful of his sandwich.

"Why were they chasing you?" she asked.

"Ah," the Doctor whispered mysteriously, "they were after a powerful magical item, of which I am the only known bearer."

The girl regarded him for a moment, and finally decided: "No."

The Doctor frowned in disapproval, affronted that the girl had seen through his story.

"Oh, okay then," he grumbled, "They wanted the instruction manual to the most powerful source of energy in the known universe. The only reason I have it is because I nicked it before anyone like them could get their grubby mitts on it."

The girl nodded, believing him this time, and started questioning him again.

"What happened to them?"

"I stopped them."

"Where did they go?"

The Doctor shrugged. "Don't know. Back to their home, I suppose."

"How did they work?" she asked, her interest escalating, "Are they steam powered?"

"I have no idea. I didn't think to ask. But between you and me," the Doctor muttered conspiratorially, "I think they were the Shi-rakh, a race of cyborgs from the Vosko Nebula."

"But they were mechanical," professed the girl, apparently unintimidated by the Doctor's fantastical conclusion. "They had valves, and pistons."

The Doctor frowned. She couldn't have been older than six, so her knowledge was rather impressive. "So they did. Well spotted."

"I want to be an engineer when I grow up, like my brothers," she said.

"Good for you," the Doctor articulated, munching on his surprisingly delicious sandwich.

"Papa said that a girl can't be an engineer. He said it was silly."

The Doctor shrugged. "Then he's an idiot."

"He says I should learn to do cooking and sewing," she moaned.

"What is this? The nineteen twenties?" the Doctor grumbled. "Oh yes, I suppose it is. But never mind him. What do you want to do?"

"I want to be an engineer."

"Well, there you go then - be an engineer. Work hard. Don't let anyone tell you what to do."

The girl smiled at him.

The Doctor finished his lunch, and slid the plate to one side.

"I have to get back to the TARDIS. It was nice to meet you, uh…?" the Doctor smiled apologetically, "I'm sorry, what was your name?"

"Clara," the girl chirped.

The Doctor's hearts twinged, and his smile wavered for a moment. He inclined his head ever so slightly.

She frowned, noticing the pain in his ancient, shimmering eyes.

He quickly masked his discomfort with a smile.

"Enjoy your future, Clara. I have everyone else's to attend to."

The Doctor stood up, and headed back down the train, as it steamed through a small town, disturbing the residents, their windows rattling from the intense vibrations caused by the speeding locomotive.