The Doctor gave a soft smile as he watched Wyn and Stella bring the TARDIS to a smooth, untroubled stop.

“Well done,” he said to them. “I’ll make TARDIS pilots of you, yet.”

“How come it lets us?” Stella asked. “Isn’t there something about you and it being connected. What’s the word…”

“Symbiotic,” Wyn answered her. “It’s called Rassilon’s Imprimatur. I read about it in the TARDIS database. “It SHOULD only operate for The Doctor. He is the one the TARDIS belongs to, and whom it recognises. Although, of course, in mum’s time the Time Lords had rigged it so that it didn’t do what he wanted. They could summon him and the TARDIS whenever they wanted and send it to any place they wanted to make him do their dirty work for them.”

“I sorted that out eventually. Overrode their control.”

“They revoked your exile and let you have control of the TARDIS,” Wyn reminded him. “MUM knows all about it. She told us. Even then, you were HOPELESS. She sometimes wondered if she would ever get home.”

“Your mum never really minded. She loved being with me, travelling the universe. It was Sarah Jane who REALLY got the worst of it. I was free at last and I really went out of my way to avoid Earth. So many more interesting places to visit.”

“And unless you went back to Earth she couldn’t think of leaving?” Wyn looked at The Doctor. He didn’t answer that, but there was a look in his eyes that told him she had hit the nail on the head.

“When you three have finished talking about the good old days,” Jamie said. “Would you like to know where we are now.”

“Las Vegas,” Wyn answered. “That’s where the co-ordinates I set were supposed to bring us. July 31st, 1969. To see Elvis Presley’s first Vegas concert and prove to The Doctor that the Vegas sound is WAY better than the old rockabilly style of the ‘50s.”

“Er… No.” Jamie replied. “We seem to be on the right continent. But we’re not in Las Vegas. And we’re not in 1969. According to the temporal location monitor it’s April 24th, 1906 and according to the spatial monitor we just crossed from Iowa to Nebraska at the city of Omaha while we were talking.”

“What do you mean CROSSED?” The Doctor demanded and bounded around the console to view the data screen Jamie was looking at.

“Come to think of it,” Stella pointed out. “We DO seem to be moving still. I thought it was just me. I never know if the TARDIS is coming or going or got there half the time. But can’t you feel it?”

“We’ve landed on something moving,” Wyn said.

“A train,” The Doctor confirmed. “Judging by the speed and the resonance of the vibrations, and the fact that you’re not being travel sick, Wyn. Apart from the TARDIS, a train is the only other vehicle that doesn’t make you nauseous.”

“A train in Nebraska.”

“Steam train to be precise. A steam train in Nebraska in 1906.” The Doctor grinned. “Period costume in the wardrobe, children. Jamie, do you want to be one of the guys today. Utah is the next state along the Union Pacific Railroad and people might get funny ideas if I’m seen accompanying three women.”

Jamie smiled blithely and shimmered. The good looking male form looked odd in the skirt suit she had been wearing but he kicked off the high heeled court shoes and went with Wyn and Stella to find the huge cavern of a room that had clothes for every occasion. The Doctor checked their continued movement literally under someone else’s steam and double checked on the historical database what he knew about late April, 1906, before he followed them.

A half hour later they emerged from the TARDIS, The Doctor and Jamie dressed in tweed suits and fedora hats. Wyn and Stella were in neatly tailored linen skirts and blouses with matching waistlength jackets buttoned up to the neck and flat brimmed hats with ribbons around them.

It took them about twenty seconds to realise their clothes weren’t quite right. Ten minutes later they re-emerged with long overcoats over their clothes and hats fastened down with scarves. Wyn, Jamie and Stella found themselves a place to sit among the tarpaulin covered bales on the flatbed wagon that the TARDIS had materialised upon. They pulled a blanket around them that they had brought with them and settled down to watch the scenery pass them by. The Doctor examined the cargo before sitting down with them. The long train, consisting of at least three of these flatbeds, a dozen or more box cars and five Pullman cars for passengers was travelling through some very beautiful countryside. The sun was high in a clear blue upturned bowl of a sky at just after midday on a spring afternoon. A sparkling river wound its way alongside the railroad, catching the sunlight. Beyond it was rolling prairie that made them all think fondly of the plains of El-Roah and far, far beyond, a mere smudge to the south, were some hills or mountains.

“It’s the River Platte,” The Doctor told anyone who wanted to know. “Named by French settlers from their word for ‘flat’ because it is such a wide, lazy river. Sixty or seventy years ago, before the railroad was pushed through to the west, pioneers in their covered wagons followed the river on the Oregon trail and the Mormon trail to Utah.”

“That’s our history and geography lessons for today,” Stella teased him. “So are we going all the way to wherever this train is going in the open air?”

“It’ll stop at some point to take on coal and water and for the passengers to buy food. We’ll get a more comfy seat then.”

“Where IS it going?” Wyn asked.

“California, eventually,” The Doctor answered. “It’ll take until about mid-morning of the day after tomorrow to reach San Francisco – or as close as they can get to it.”

“Why ‘as close as they can get’?” Jamie queried.

“It’s April 24th, 1906.” Jamie, not being Human, and having lived, when he did live on Earth, in the fifty-first century, could be forgiven for not recognising the significance of a date in the early 20th century. Wyn and Stella came from a century later. They might have seen films or documentaries, but it wasn’t something that came to mind instantly.

Six days ago,” The Doctor continued to explain. “A devastating earthquake hit San Francisco, followed by aftershocks and fires that destroyed what the quake didn’t. This isn’t an ordinary train. It’s a relief train bringing supplies. This flatbed has canvas for tents. There’s another one there with lumber. The enclosed boxcars will have sacks of flour to bake bread and other foodstuffs to feed the refugees. Then medical supplies. Morphine, antiseptics, bandages, splints, headache powders.”

“Oh!” Wyn looked at the long lines of freight cars as the locomotive way at the front turned a graceful corner and they could see the full length of it properly. She had thought it was just ordinary goods being transported across country. But if The Doctor was right, it was much more than that.

“That answers the question then,” Jamie decided. “We’re going to the end of the line. Elvis can wait. We can all help. They need people as well as food, don’t they? Doctor, I’m sure there’s plenty you can do. You’re a Doctor. And the rest of us can help somehow. We’re fit and healthy and not afraid of hard work.”

“It’s not going to be pretty,” The Doctor told him. “I’ve been there. In fact…” He thought about it for a moment. “Actually, I AM there right now. When I was a graduate on my gap decade I was here on Earth when it happened. I came and pitched in. Did my share.”

“You rescued people?” Stella asked him. “You saved people’s lives, like a real hero?”

“The Doctor IS a real hero,” Wyn told her. “Always has been.”

The Doctor thought about that time when he landed in San Francisco in the immediate aftermath of the quake. He remembered how, like everyone else, he had sweated and toiled and broke his back shifting rubble with picks and shovels or sometimes with his bare hands, to reach people trapped in the debris. He remembered how they had sometimes found survivors, wounded, terrified, clinging to life, grateful for deliverance. Other times, increasingly so as the long hours passed, as the first day melded into the second without sleep, they found bodies. Broken, pathetic bodies, crushed by unforgiving stone and brick, steel and wood. He remembered especially a little girl, no more than five or six, who he lifted from the wreck of her home. Every bone in her body was broken. She flopped like a rag doll in his arms as he searched for a sign of life, knowing that, even if he did find a spark it would have been more merciful to snuff it than kindle it. He never knew if her parents were alive or dead. There was too much chaos in the early days and families were broken up and scattered.

Nor was that the worst of it. He remembered finding bodies so badly crushed they hardly looked like humans any more, body parts, severed and scattered with the falling masonry of the once strong, proud buildings of a beautiful city that had been the pride of the west when Los Angeles was little more than a village.

And then the fires started, and that made it worse. Now they found charred bodies. People who might have been alive, trapped in the rubble, burnt to death still hoping that somebody would get them out. And as the fires spread rescue became impossible even if anyone was left to rescue. He had been able to do more than most of those around him. He had superior strength. He had the ability to close off his breathing, to withstand higher temperatures than any Human. He could time fold and step through flames that seemed frozen in time. He HAD managed to bring out maybe a dozen more souls who would have perished otherwise.

But as the effort was finally called off and the army moved in to blow up sections of the city to try to make a fire break and save what was left, he had stood at the edge of the refugee camp in Golden Gate Park and looked at the devastation. And he had cried in despair, cried for the souls he had failed to save. Cried at his own impotence, because despite his awesome Time Lord power he could do no more than break his back and sweat blood like everyone else around him and he had barely scratched the surface of the problem.

He certainly didn’t feel like a hero. Neither did any of the people who had scrambled through the debris with him. They felt like people who had already gone through the fires of hell and had another hell still before them.

And they had. As the fires finally died he gave his time and energy, the sweat of his brow to the medical needs of the half million or more refugees, first tending the wounds, crushed limbs, abdominal injuries, broken skulls, burns of every degree, amputations and other desperate measures. Then it was gangrene and dysentery and typhus as a half a million people shared inadequate and hastily dug latrines, ate food that was rapidly going off, drank water that, even after it was boiled, was left standing in the open so that it was re-infected with bacteria. Medical supplies, like everything else, were scarce. Because the supplies were coming on trains like this one, racing across the country from Chicago, on the Union Pacific railroad that had only been completed a few decades earlier. It had thousands of miles and several States to cross to bring what was so desperately needed.

It wasn’t about heroism. It was beyond any easy label like that.

“Yes, we’re going all the way.” The Doctor said. “Yes, we can help.”

That younger version of himself had stayed as long as he felt he was needed. Once the relief started to come in from the East he quietly slipped away. He could as quietly slip in and take up the work again. Finish what he started eight hundred years ago.

For now they just sat there on the flatbed, leaning on the bags of flour and watching the train wend its way across Nebraska, close to the Platte River much of the time. They followed the sun as it dropped from its zenith towards the west. About four o’clock, just as the novelty of travelling on a flatbed car across an American prairie was starting to wear off the train began to slow. The locomotive and the passenger carriages stopped at a log-built depot with a wooden platform. There was a small town of genuine log-built prairie houses and saloons just as they had seen in any number of Western films. A sign by the platform declared this to be Brady, Nebraska.

“Here we go,” said The Doctor springing up from the flatbed as if things like cramp, dead legs and stiff backs didn’t affect him. The others were a little slower.

“Make it snappy,” he said to them as he helped Stella and Wyn down to the cinder track. “This is just a water stop. We don’t want to get left behind.”

They hurried along the side of the train until they reached the platform. The great tank on the locomotive was filled with water and coal was replenished almost as fast as a Formula One team at a pitstop. A guard stood ready to blow his whistle as The Doctor ran up to him, waving a piece of paper that turned out to be tickets for four travelling on the special train. Nobody asked how he had them in his pocket. They figured he would probably book them retrospectively some time next week.

“ Sorry we’re late,” The Doctor said as he ushered his friends aboard the train. “We won’t hold you up any more.” He took the steps up into the car in a single bound and led his companions down the centre aisle until he found four seats fixed opposite each other. As they sat down, gratefully, the train was already pulling out of the station.

“That’s a LOT better,” Wyn said as she leaned back against the soft headrest. “Upgraded from Third Class to First. MUCH more like it.”

“Yes, they’ve put on the best cars,” The Doctor said. “After all, we’ve still got thousands of miles to go. “Still, it won’t feel as comfortable after we’ve slept two nights right here.”

“We’re better off than the people we’re going to help,” Stella pointed out. “It’s nice and warm in here.”

“You seem very young to be making this journey,” said a man sitting on the opposite side of the aisle. “Are you quite prepared for what is ahead? The stories that are coming off the telegraph – bodies lying around decomposing, death and destruction.”

“I’m seventeen,” Stella answered, sticking up for herself admirably. “Nearly eighteen. And after what I’ve seen already, travelling with The Doctor, there isn’t much to scare me in San Francisco. I’m certainly not scared of dead bodies. They can’t hurt me.”

“You’re a doctor then?” the man asked The Doctor who smiled and doffed his hat in friendly gesture. “Likewise. Doctor Sam Clement of Chicago.”

“Doctor John Smith of London,” he replied. “My friends and I were travelling in Nebraska when we heard the news and decided to join the relief effort. Least we could do.”

“Very commendable of you, sir,” Clement said to him. “Still, from what I’ve heard it’s no place for two ladies. I hear law and order has completely broken down. They may not be safe. As for the accommodation we may expect…”

“We certainly don’t expect luxury,” Wyn replied on behalf of them all. “We’re going to help people who have lost everything. The Doctor – he’s a brilliant doctor. Stella is his nurse. I’m an engineer. I can help get the water supply running or the electrical power. Jamie is a policeman. She… I mean he, can help do something about that law and order problem. And if there’s nothing else to do we can all make soup and feed hungry people.”

“Quite right,” said another man in the seat behind Mr Clement. He was wearing the clothes of a Catholic priest from the turn of the twentieth century. “I have been sent to pray for the dead and make sure the Good Word is heard by those in distress. I understand mass graves and cremations are the order of the day. But the bereaved will no doubt need a kind word. And when I am not praying, I, too, can distribute food, erect tents, change bandages… whatever is needed.”

That was the story with each of the passengers on this train. They all had some skill that could be useful in the disaster area. But above all they were fit and healthy and ready to turn their hand to whatever needed to be done. They were all prepared to give their all and then some to help others. News sent by telegraph across the vast nation had left them with few illusions about how bad it would be, but still they came, leaving their own work, their families, to do their bit.

The Doctor smiled proudly. It was times like this when he knew why he loved humans. His own people were so powerful and mighty, but they wouldn’t know where to start if a disaster like this hit them. Humans! Such adversity brought out the best in them and they rose to the occasion and made him so very proud of that bit of his DNA that came from their species.

But the hard work was still ahead of them, yet. All they could do for now was sit back and watch the Nebraskan prairie flying past, watch the sun race ahead of them towards the far off horizon where the dome of the sky met the land. They talked among themselves quietly. They chatted with other passengers. When their legs were tired from sitting they stood and walked the wobbly walk of train passengers everywhere to the end of the long carriage, where there was a faucet and a small metal basin with a drain for the excess water. A tin cup was hooked next to it and the water that came out was surprisingly cool and refreshing. Beyond the door at the end of the carriage was a toilet facility that was as good as anyone might expect in 1906 and, Wyn said, a little sarcastically, slightly better than some trains she had been on.

The sun had just set very spectacularly and beautifully when Jamie glanced surreptitiously at the display on his wristlet and announced that they had just crossed the State line between Nebraska and Wyoming. Not long after that the train began to slow and eventually stop in another prairie town with a rail depot. This one was called Pine Bluffs for the cliffs that rose up behind the town. The pines were still visible against the now darkening sky as water and coal were taken on board again and people came onto the train selling cool milk and hot potatoes with pats of butter or wheat and oat bread. The Doctor purchased some of the food for them. It was an unusual supper, but one they enjoyed all the more for being hungry for it. The TARDIS kitchen and the vending machine in the corridor near the engine room were inaccessible and none of them had been able to ‘snack’ as they were used to doing. They made the most of their meal as the train jerked and jolted and started off again.

“Look at that man,” Stella said and they all leaned over to the window to see a tall man in a black suit running to catch up with the train as it began to gain momentum. They saw him jump for it and a moment later he hurried along the aisle looking for a seat. Stella noticed that another man had run onto the platform and seemed to be yelling something. But the train was moving too fast already and Pine Bluffs was behind them before the new passenger had found a seat near the water faucet.

The Doctor and Jamie were looking at each other. Wyn noticed that The Doctor had his sonic screwdriver concealed in his hand and Jamie was examining his wristlet display. He mouthed something to The Doctor who shook his head.

“I thought… for a moment… a trace…” he said.

“Me, too,” Jamie replied. “Just for a moment as that man walked by.”

Wyn looked at the man they were talking about. He was an odd looking character. His flesh seemed grey and pallid, and his eyes bulged like a startled fish. She watched The Doctor get up and go to the faucet. He took a half cup of water and drank it slowly. As he did, he seemed to be sniffing the air, as if detecting gas. He put the tin cup back and returned to his seat. Again he shook his head.

“I’m really not sure,” he told Jamie. “It could be nothing. But let’s keep an eye on chummy there.”

“Is there any chance you’re going to tell me what you two are thinking?” Wyn asked.

“Not here, not yet,” The Doctor answered. “Not unless there’s more to go on. Eat your supper. The next stop isn’t until about two o’clock in the morning. And we won’t be able to buy breakfast until the next stop after that at about seven.”

“These modern locomotives are remarkable,” said Doctor Clement to them. “When I was a lad, when the Union Pacific had only just been built, they would have to take on water every hour. Now we can cross half a State without a stop. Imagine the progress we might yet make.”

“Indeed,” The Doctor replied with a smile. “Fast, uninterrupted transport across a continent. And yet there is something pure about a steam train. It isn’t easy. It’s still about effort. A man stokes the coal into the furnace. Another drives the train. I always dreamt about driving a steam locomotive. When I was a boy I imagined what it would be like to have such a magnificent machine under my hand.”

The Doctor’s eyes glittered as he spoke. Wyn looked at him and wondered why he was so enthusiastic. He had the TARDIS under his hand always. It was the most powerful mode of transport in the universe. Yet he looked excited about the idea of driving a steam train, which was the first step up from horse drawn carriages that mankind had made. She wasn’t sure she understood the attraction for somebody like him.

“I’m a control freak,” he whispered to her. “The idea of being in control of something as big as this train, yes, it’s exciting. EVEN for me.”

“You’re mad,” Wyn told him.

“Yep,” The Doctor grinned. “That sums it all up!” And he leant back in his seat and looked as if he was relaxing, though Wyn suspected he was still taking in everything in the lamplit train car from under his half closed eyes. If he could see with his eyes completely shut it wouldn’t surprise her.

As the evening passed the passengers relaxed. They played cards or read newspapers that carried reports from the disaster they were heading towards. They talked among themselves. Some smoked pipes or cigars, long before the time when smoking was banned on trains. Wyn felt herself drifting into a comfortable snooze with her head against the high backed seat. Jamie and Stella did, too. The Doctor seemed to be in one of his light trances where he let his mind slow right down and his body refresh itself much faster than ordinary sleep.

The need to use that toilet facility just beyond the door of the carriage woke her from her snooze and she got up and made her wobbly way along the aisle. She was near the strange man in black from Pine Bluffs when the train jerked slightly, as it did from time to time. She lost her balance and bumped against the seat.

“Oops, sorry,” she said automatically, but the man from Pine Bluffs didn’t respond. She looked at him and jumped back in shock as he slumped over the seat. Her yelp of surprise alerted everyone nearby, but it was The Doctor who reached her side first, switching from trance to wide awake and bounding from his seat instantly. He waved Jamie back into his seat and called to him to keep Stella with him for the moment. He heard Stella huff at being told to stay away from the excitement, but teenage moods were not his priority right now.

“He just keeled over,” Wyn said. “Is he dead?”

The Doctor concealed his sonic screwdriver in his hand as he turned the man over and examined him. He certainly looked dead. His eyes were unseeing and unresponsive and his body limp.

And yet…

“No, he isn’t!” The Doctor exclaimed. “Not yet.” He looked around at the curious onlookers standing up in front of their seats or in the aisle. “Doctor Clement, may I borrow your medical bag, if you please?” Doctor Clement willingly handed it over to The Doctor who looked inside and found what he needed. A very large syringe with a huge steel needle. He began to roll up his own sleeve and then inserted it in his upper arm. Wyn realised what he was doing and took over extracting blood from him. When the syringe was full he pushed up the victim’s sleeve and injected it into his blood stream. Almost immediately that unusual remedy took effect. His skin became less grey and the eyes less bulging. He gasped for breath and his eyes focussed normally as he reached out and grasped The Doctor’s sleeve and tried to pull himself upright. The Doctor put his arm around his shoulder and helped him up.

“Where am I?” he asked. “How did I get here?”

“You’re on a train, headed west,” answered The Doctor. “You jumped aboard at Pine Bluffs a couple of hours ago. You don’t remember doing that?”

“I don’t remember doing anything like that. I remember being in my office. I’m the telegraph operator at Pine Bluffs. The last thing I remember was a man walking in. I didn’t know him. He was dressed like a sharecropper. Not the sort that usually came in to send wires. And, in any case, this one looked more like he needed a doctor not a telegraph. His eyes looked like they were popping out of his head and his skin was grey. I asked if I could help him, and he… I don’t remember what he said, but he reached out his hand. Touched me on the shoulder. And that’s the last thing I recall. I remember… I think I could hear a train in the distance. It would be this one, I suppose. But I don’t remember getting on it.”

Wyn looked at the man again. The description he gave of the ‘sharecropper’ whatever one of those was, fitted how he looked five minutes ago. Now, apart from looking puzzled and a bit pale he seemed nearly normal.

“You had some kind of blackout,” The Doctor told him. “Wandered onto the train by mistake. You’re fine now. Your only problem is this train isn’t stopping again until Medicine Bow and you’ll probably have a long wait to get one back the other way again. But you just sit tight. Wyn here will ask about and get some food and something to drink for you. You’ll be grand.”

Wyn went to do as he said and came back with some donated oatcakes and milk and a tot of whiskey that perked the man up quite a bit. Meanwhile The Doctor slipped the syringe into his pocket and brought the rest of Doctor Clement’s medical equipment back to him. He sat and waited until Wyn joined him then leaned forward and spoke to his three friends quietly.

“There’s trouble on this train,” he said. “Jamie, you know what a Killik is, don’t you? You smelt it, too, when he passed by.”

“It’s a sort of internal vampire,” Jamie answered. “Rather than drinking the blood of its victims it enters their bloodstream and consumes the blood from within, red and white corpuscles, platelets, until all that remains is the plasma – essentially water running through the veins.” He gave a word perfect text book answer and then swore a very rude Haollstromnian oath. “That’s what we have on this train?”

“That sounds bad,” Stella added.

“It’s beyond bad,” The Doctor said. “It’s a trainload of bad. This thing had at least one other host at Pine Bluffs. The man who came into the telegraph office. It migrated from that body to the telegraphist, who hopped the train. Now it’s in another body, somewhere on this train.”

“Oh, bloody HELL,” Wyn swore. “And it kills them, usually? That man only survived because you helped…”

“It finds a new host before it kills the one its in. But by then the blood is so used up the body can’t survive. My blood gave that man enough respite for his body to start producing new blood. He’ll be a bit anaemic for a day or two, but he’ll be right as rain after that. One of the FEW advantages we have with this thing is that it can only take one victim at a time. It’s not like your common or garden vampire that attacks multiple victims. The disadvantage is that it has only just migrated. The greyness and the bulging eyes won’t start to manifest for a half hour or so. At the moment the only way to recognise the host is by the smell. There’s always a faint odour like raw black pudding. And humans wouldn’t detect it, anyway. I can. And Jamie can because he is so used to detecting other people’s pheromones that any other kind of scent overwhelms him.”

“How long does it take?” Wyn asked. “For the host to get ‘used up’ and the Killik to move on?”

“About two hours,” The Doctor answered. “Our man there said he heard this train coming before he was taken over. It’s been two hours since Pine Bluffs and the Killik migrated to another host. We need to find it in the next two hours before it needs to move on again.”

“So what do we do?” Stella asked.

“YOU aren’t doing anything.” The Doctor told her. “You’re going to go and sit next to Father Burke there and let him read Bible passages to you. You’ll be safe. The way we all prefer you. Jamie, you’re going to sniff out the Killik host for me. Wyn, you go with him and when you find it…” They saw him roll up his sleeve and fill the syringe again with his own blood. He corked the needle and passed it to Wyn. “When you find the host, use this. My blood mixed with Human blood will burn the Killik out. It won’t be able to tolerate a Human-Time Lord cocktail. Or… if it’s already migrated to a new host, you might just be able to save another man’s life the way I did before. That’s your judgement call if I’m not back by then.”

“Where are you going?”

“I’m getting off the train for a bit,” he answered. “I just want to check out what happened at Pine Bluffs. Make sure there are no more of those things. I’ll be about half an hour, I hope.”

Since Pine Bluffs was already hundreds of miles back and the train was still speeding westwards that really DIDN’T make any sense to anyone who might have been eavesdropping on the conversation. But The Doctor’s friends just worried about being separated from him.

“Don’t get lost,” Wyn told him. “And be careful.”

“Careful is my middle name.” he answered.

“Like hell it is,” she replied with a grin that matched his. Stella looked crossly at him but as he passed her sitting next to the priest, he could feel her real thoughts. She didn’t WANT to go hunting an entity that could eat her blood from inside her. The thought of it terrified her. Being ORDERED to stay put gave her the excuse to pretend she minded being left out.

Wyn and Jamie headed in the opposite direction to The Doctor. They passed through the door at the end of the car and went past the toilet facility to the outer door. Wyn expected beyond it one of those wobbly linking tunnels between carriages, draughty and noisy, but more or less sealed inside. Instead, they found themselves on a sort of ironwork veranda at the back of the railcar. A few feet away was a similar one on the next car. And between the two were steps down and a gap that they had to step across.

“Oh!” She wondered if it was better to have eyes open or closed. She decided open was probably best in the long run because if she missed her hold of the handrail opposite….

She stepped across. She reached the ‘safety’ of the other veranda. She waited until Jamie followed her then they opened the door to the next car.

“Hello,” she said brightly. “We’re just taking a stroll. Don’t worry. Did anyone else come this way in the past couple of hours?”

“Only the ticket collector,” said a man in a tweed suit not unlike the one Jamie was wearing. “He wasn’t very interested in tickets.”

“Did he look ok?” Jamie asked.

“Not really,” answered the man. “A bit grey, sickly looking.”

“Thank you,” Jamie told the man. He turned to Wyn. “Three more cars to check. Sorry.”

Wyn groaned.

The Doctor found the door at the back end of the car locked, but his sonic screwdriver made short work of that and he stepped out onto another ironwork platform. But behind this car was a boxcar and it had no matching platform. There was a ladder fixed to the car, but the gap was much wider and The Doctor, with his Gallifreyan eyesight, could see much clearer than Wyn the railway sleepers and the cinder road flying past underneath. He wondered about his chances of regeneration if his body was minced under the length of this train and decided that he had better not miss when he jumped.

He didn’t miss. He grasped the ladder firmly and climbed it quickly, reaching the top of the boxcar where he wondered if the ladder was actually safer. It was less windy and he had something to hold onto. But there was nothing for it if he wanted to reach the TARDIS. He walked nimbly across the top of the car and judged the distance between this car and the next one. He jumped and landed with inches to spare. He stood up and carried on.

“I could have RETIRED!” he told himself as he walked quickly to the end of this second car and got ready to jump again. “I could have retired to any peaceful planet in the universe. I could have stayed on Forêt and watched my grandchildren become grandparents. I could have gone to Malvoria and contemplated the wonders of a snowflake for peaceful days on end. I could have gone to SangC’lune and been treated as a god by the people there. But Noooo! I’ve got to be a hero. I’ve got to go and stick my daft nose in other people’s problems.”

He laughed and jumped again and moved quickly on, glad that, at least, the open prairie didn’t have any BRIDGES he had to look out for.

He reached the last box car and looked down at the flatbed full of lumber. He mustered his strength and begged his past incarnations to lend him their strength, too, as he jumped and hoped for a less painful landing than he was expecting.

He landed badly, winding himself and jarring his ankle, but he only had one more jump to make. He could see his TARDIS on the next flatbed, among the bales of canvas. He ignored the bruises and carried on.

“My TARDIS!” he cried as he scrambled over the bales and reached for his key. He unlocked the door and stepped inside. He felt as if he should kiss the console. He didn’t. He simply patted it lovingly and then put it into hover mode. It rose above the train and moved east as the train moved west, soon leaving it behind as he set the course for Pine Bluffs.

Wyn had her hand on the door that led into the third car when Jamie laid his hand over her arm and stopped her. He pointed to his wristlet which was indicating the presence of something not Human behind the door.

“Quietly,” he said. “Carefully.” And he pushed the door open in time for them to see the ticket collector fall to the ground as another man turned and ran. Jamie started to give chase but stopped as he saw Wyn bend over the ticket collector with the syringe of The Doctor’s blood.

“No,” he told her. “We can’t. We still have to get the one that did it. It’s switched hosts. You saw it.”

“The Doctor gave us the choice. Stop the creature or save one more man’s life.”

She looked up at her lover as she held the dying man in her arms. Their dilemma was clear. Jamie had spoken the truth. Yet COULD they just abandon this man to a terrible death?

“He might not die,” Jamie told her. “The Killik switched hosts much faster this time. Because it knew we were pursuing it, I suppose. He won’t be so badly affected.” He knelt and used his wristlet to run a basic medical scan. “He still has about half his normal blood cells. He’ll be very ill, anaemic. But he might survive.”

They carried the ticket inspector through to the main part of the car. Two men identified themselves as doctors and took charge of him. They didn’t quite understand Jamie’s explanation of what was wrong with the victim, but they would do their best.

“The man who ran through here…” Wyn asked. “We only caught a glimpse….”

“A soldier, from the front car,” she was told. “He came through here before. A disgrace to his uniform. He was drinking and trying to offer liquor to the rest of us.”

“There are soldiers up front?” Jamie asked.

“A company of riflemen. To maintain martial law in the devastated areas,” was the reply. “Good men, most of them. But every barrel has a bad apple…”

“Ok.” Wyn said. “We’ll catch up with him. “You look after this guy.” She looked down the car to the far door and groaned. “More gaps to get across.”

The Doctor landed the TARDIS at the railroad station of Pine Bluffs. He looked around and noted a light burning in the telegraph office. Since he knew the telegraphist was on his way to San Francisco, that immediately looked suspicious so he headed that way.

He wasn’t sure what to expect, and a gun in his face was on the list of possibilities, but not near the top.

“I’m unarmed,” he said calmly. “I’m The Doctor.”

“You’re too late,” said the man with the gun as he holstered it. The Doctor saw a sheriff’s badge on his waistcoat breast before he looked past him and saw the body lying on the floor. He was wearing a handmade linen shirt and rough denim trousers, both well worn like his working man’s leather boots. He fitted the description of a sharecropper who had no business to do in a telegraph office.

And The Doctor didn’t need to get any closer to confirm that he was dead.

“How many more are there?” The Doctor asked with a grim look on his face.

“How did you know there would be more?” the Sheriff asked.

“I know what caused this. I know that the deaths are never isolated. There will be a pattern. A chain. I’ve seen a whole space… a ship… a ship full of people… all killed this way, one by one.”

The sheriff, of course, imagined a ship on the Atlantic ocean, bringing immigrants to America, packed into steerage where a disease could take hold.

What The Doctor was thinking of was a space ship doing a similar job but taking people to a remote colony in deep space on a journey that took as much as four years. The one he had found dead in space was two days away from its destination and had one last man with bulging eyes and a grey face who would have died shortly after arrival, passing his ‘infection’ onto the billion strong population of the colony planet.

If The Doctor hadn’t set the ship’s engines to go into overload and explode, reducing everything aboard to atoms.

“All his family are dead,” the Sheriff said. “I saw them earlier. The Minister of our church found them and reported it to me. I was just back from the farm when I saw him come into here. And then Matthews, the operator, came out and started running for the train. I don’t know why he did that. But if this is an infectious disease… we should quarantine the town. That train…”

“It’s not a disease as such,” The Doctor said. “I would go and look at your sharecropper family if I had time, but I don’t. Is their farm isolated?”

“Yes. These prairie farms tend to be,” the Sheriff answered.

“Then it was contained. That’s a blessing. Have the bodies burned. This one, too. And count yourself lucky the carrier left town. Pine Bluffs will live. I have to catch up with that train. Half a million displaced souls in San Francisco… It would be unstoppable.”

“What would be unstoppable?” the Sheriff asked. But nobody answered. The door swung shut behind The Doctor. The Sheriff ran outside and heard a strange, organic yet mechanical noise and felt a breeze that seemed to come from nowhere. He saw no sign of the mysterious Doctor, the complete stranger with a peculiar aura of authority, who had given him instructions he knew he was going to follow without question.

Though he DID wonder how The Doctor intended to catch up with a train that left Pine Bluffs two hours ago and would be approaching the Utah State Line in another hour.

Wyn and Jamie ran into the last car and stopped when they saw soldiers who had been relaxing and preparing for much needed sleep reach for their weapons. Jamie raised his psychic paper high and declared himself to be a Pinkerton agent tracking down a fugitive.

“He killed one of your men and took his uniform,” Jamie said. “Did he come this way?”

“Yes,” answered one of the soldiers as they put their guns away. Jamie nodded and ran. Wyn followed him.

“Pinkerton?” she queried as they reached the outdoor platform.

“Detective agency in 19th and early 20th century America,” he answered. “They’re actually a forerunner of the Time Agency. My boss has a copy of one of their warrants on his office wall.”

“Clever,” she agreed. “But what about this?”

THIS was the coal box behind the locomotive. It was a solid wall of iron with a very narrow, very flimsy looking ladder set on the back.

“We’ll have to climb over it,” he said.

“I’m wearing an ankle length SKIRT!” Wyn protested. “I’ll never…”

Jamie looked at her and grasped the skirt. He yanked it off. Beneath it she was wearing knee length authentic 1906 knickerbockers. He winked and made a joke about ‘nice drawers’.

“I’ll give you drawers,” Wyn answered. “If you really WERE a man, I’d hit you for being so ungentlemanly.”

“That wouldn’t be very ladylike, would it?” Jamie answered. “Come on. We can’t hang about.” He jumped for the ladder and caught it deftly. Wyn groaned and jumped, too. She was less precise and for one heart-stopping moment her hand slipped and she dangled perilously above the cinder track and sleepers that sped away under the train, then she followed Jamie up the ladder and dropped into the coal box.

There wasn’t a lot of coal in it. They were due to stop at Medicine Bow to refuel. But there was enough to make the scramble across it uncomfortable and leave their clothes covered in black when they climbed up the other side and jumped onto the footplate of the locomotive itself.

They just had time to take in three things. First, the fireman lying across the floor, a gash across his head and his own spade with blood on it.

Second, a man in a soldier’s uniform with that familiar grey skin and bulging eyes lying across the fireman.

Third, the train driver staring at them. He, too, had bulging eyes and beneath the coal black he might well have been grey-skinned, but it was hard to tell. Wyn reached for the syringe. She got ready to stick it in the driver, but she was too late. She saw him lunge for Jamie, his hand grasping his shoulder and pulling him as if he was no weight at all. She saw the driver bite him in the neck and Jamie’s scream. The driver collapsed in a heap on top of the other two men and Jamie turned to look at her, his eyes no longer his own.

“Help… me…” he cried. “Wyn… it’s taking me!”

“Oh no it ISN’T,” she replied and she jabbed the syringe into her lover’s neck and pressed down, forcing The Doctor’s blood into his veins. Jamie screamed again, and his eyes watered as his body convulsed and shuddered. Then Wyn saw his face and exposed arms become brilliant white for a brief moment as if something had passed out of his body through the pores of his skin. She understood what had happened. The Killik had been killed by the Human/Time Lord blood cocktail The Doctor had described. And the Time Lord portion had expelled the molecules of the entity.

“Jamie?” she asked cautiously as he steadied himself and stood up.

“Yes,” he answered. “It’s me.” He shimmered and took on the female form that Wyn loved wholeheartedly and hugged her tightly for a long moment. Then she turned and stared at the bank of levers and knobs, dials and gauges that looked far more complicated than the TARDIS console.

“We’ve got a big problem,” she said.

“What?” Wyn asked.

The TARDIS followed the railroad in hover mode, speeding along as fast as The Doctor dared make it go, which was far faster than any train would travel this railroad until the 26th century when wheels on rails were replaced by anti-gravity pads that skimmed sleek, bullet shaped locomotives along at nearly sub-sonic speeds. He caught up with the train as it raced past Medicine Bow, where it was supposed to stop for refuelling. He knew then that there was something else wrong.

“Runaway train,” Jamie answered her lover’s question. “We should have stopped back there for refuelling.”

“Well… hit the brake or… whatever…”

“It’s not as simple as that. I don’t even know which of these IS the brake. And…”

“Well, if we’re low on fuel, won’t it just stop?”

“Yes,” Jamie answered. “if the coal just runs dry. But… If the water tank goes dry before the fire dies out… I think… I’m pretty sure it will blow up the engine. And we’re standing right by it. And the train will almost certainly derail.”

“There’s another problem,” said The Doctor’s voice and they both turned to look. The TARDIS had come to a stop on top of the coal box. The Doctor stepped out of the door and jumped down onto the footplate. “Fort Steele bridge over the North Platte. At this speed the train will plunge right over into the river.”

“So what do we DO?” Wyn asked. “Doctor…”

“You get out of the way and let me drive,” he answered as he stepped past them both and quickly examined the mass of gauges before beginning to turn handles and pull stoppers and switches. They felt the train starting to slow. Wyn dared to look out at the side and saw the bridge ahead, and the river reflecting the starlit sky.

“We’re not going to make it,” she said.

“Yes, we ARE!” The Doctor answered. She was surprised to see that he was grinning. She remembered what he had said a few hours ago about wanting to drive a steam locomotive.

“But you don’t KNOW how to drive a train!”

“Well, I didn’t. But you know what a fast reader I am. I read the manual on the way back from Pine Bluffs.”

Wyn wondered if he was joking or not. But either way he DID seem to know how to drive a steam train. More importantly, how to slow it down to a safe speed as the bridge loomed ahead. They felt the difference in the vibration as the locomotive moved off solid ground and onto the ironwork bridge across the North Platte river. But the crisis was over. It was going at the right speed and as soon as it was across The Doctor began slowing it still further until it came to a smooth stop at the rail depot of Fort Steele.

The Doctor jumped back into the TARDIS and moved it out of the coal box before fuel was dropped into it. He parked it by the toilet facility in the rear passenger car. Wyn nipped in to change her clothes. By the time she was done, the train had coal and water for the next leg of the journey. Meanwhile the last victims of the Killik were all being treated for their blood loss and recovering in a hastily arranged mobile infirmary in the army car. And when the train set off again, The Doctor was joyfully driving it, with one of the soldiers commandeered as fireman.

A day and a half later they reached Sacramento, where a Union Pacific driver insisted on taking over from The Doctor and making him return to the passenger car. He rested for the further hundred miles the train was able to get, to the town of Santa Clara. From there a caravan of horse drawn wagons took the freight and the people to San Francisco.

Finally they arrived at Golden Gate Park and for a while they just stared at the scene before them. Wyn and Stella thought of some of the disasters they had seen on TV in their lifetime. Jamie thought of some of the desperate situations he had seen in his life as a Time Agent. Nothing compared to standing there, looking at a tent city of half a million survivors of the devastated city that they could see beyond the park. They all wondered how anything was ever going to be salvaged from this. How DID San Francisco become a living city again?

The Doctor didn’t wonder. He knew what humans were capable of in the face of adversity. As his companions were detailed work to do he headed to the medical tent. He watched a dark haired young man who hardly looked old enough to be a doctor tending to the wounded and sick. He was good. Crying, feverish children were calmed by the touch of his hand. Pain melted away under his caresses. He looked tired though. Even for one of his kind. The Doctor remembered that he had not slept for more than two hours in total in these frantic, terrible days.

The young Time Lord stood back from caring for one of his patients and looked around. He saw The Doctor and stared at him as if he felt he knew him but wasn’t sure how or why. He stepped closer. The Doctor felt the telepathic connection in his head.

“You’re….” he stammered.

“I’m here to take over. You’ve done your share. You can go with a clear conscience.”

“I can’t JUST go. I’ll go tomorrow. After I’ve made sure everyone is ok. Until then, you go and make yourself useful somewhere else. Where you won’t cause a paradox. They need help making the food. You still know how to peel potatoes, don’t you?”

The Doctor laughed. His younger self, who ought to have recognised him as his superior in every way, had just given him the brush off. And after all he had done to get there!

But as he turned away and let him get on with the job, he remembered now, that was exactly what he HAD said to himself when he turned up.

He went and happily peeled some potatoes.