THE FUTURE MUSEUM

Friedrich Köhler was tense, alert, and listening for footsteps that would signal an instant death. All he heard, as he shuffled through a puddle, was the tinkle of his splashes echoing softly across Montmartre hill. It would happen soon, though. He had sensed someone watching him all evening. Tightening his grubby moleskin coat around himself, he bent a balding head in the direction of the Basilica of Sacre-Coeur and his little appartement.

The door, he discovered with a stab of surprise, was already open and a pale glow reached warningly through the crack. Köhler stiffened. This, he knew instinctively, was it. His thin features set into a look of grim resignation, he stepped inside.

A man was lounging contentedly in an armchair, nursing a bottle of Armagnac.

"Don't mind, do you? I was parched. You know what it's like."

Köhler squinted, confused. The stranger had boyish brown hair and a wiry body that was almost lost beneath a double-breasted sack suit, thick Raglan overcoat and striped, spongebag trousers. He seemed to be in his middle thirties with a thin, pale face that somehow managed to be both convivial and cold, and spoke with an English accent.

"Drink with me!" he demanded and raised the bottle in the air. The little that was left slopped guiltily in the glass. "Actually, do you have anything else? I'm in the mood for a malt, for some reason."

"I don't know you," said Köhler stoutly.

The Englishman sneered and shook his head with cynical amusement. "Well, I know all about you, Friedrich Köhler. For one thing, I know that isn't your real name." With a squeak of leather upholstery, he leapt restlessly to his feet. His whole body, it seemed, surged with insuppressible energy. "You aren't German, either," he continued, "and you don't usually look this way. The real Köhler worked for the White Star Line and died on the Titanic. He was a second cousin to the Duke Gerhard of Württemberg. You wrote to his business secretary in Strasbourg and claimed to be Köhler, impoverished after the disaster, and asked for two thousand marks so that you can recover all you have lost. I intercepted the last of these letters and shall show it to Inspector Juve of the Sûreté, if we can't come to an arrangement of our own. I'll settle for a brandy if that's all you've got in."

Friedrich Köhler seemed too indignant to even speak. "These – these are lies!" he blustered, trembling now.

"No," said his guest pithily. "You're Vincenzo Peruggia, a thirty-one year old Italian thief who committed the world's most audacious art theft last year when you stole the Mona Lisa."

The other man paused, cautious and thoughtful. "I do have some malt," he allowed. His accent was now conspicuously less German. Turning to the sideboard, he picked up a bottle of whiskey and poured a glass. A keen observer would have noticed how the narrow shoulders had folded confidently back and he was no longer trembling.

"So," said the Englishman, and clapped his hands briskly together, "do I have to inform the police?"

The word was like a curt command. Vincenzo Peruggia whirled around and hurled the bottle into the hearth. With a dull rumble, the fire swelled angrily outwards, spitting sparks across the carpet and onto the sheepskin rug. The visitor made to move, but a forceful shove sent him reeling backwards into the chair, upending it onto the floor.

How had this whippet of a man found him? The very fact he had done so was embarrassing. Emasculating, even. Vincenzo Peruggia threw off his bald cap disdainfully, unsheathed his coat and knelt over his guest. A glint of silver, and he was suddenly holding a knife. "Tell me, signore," he growled, "who are you? I want to know what to carve on your grave."

The young man stared indulgently up at his host with eyes of dark humour and dangerous intent.

"I'm the Master," he said, and smiled.

Jaz delved into the washing basket, pulled out a pair of smart trousers, and wondered if she should hang them. Since the accident, her father barely ever left the house, so it was not as though he would need them. He needed nothing, in fact, from his town council days. Jaz could hear the television from the kitchen window – Eggheads, as usual – and knew he was sitting sullenly in front of it.

It wasn't fair. He was still a young man, really. Other people were allowed to wander around and do whatever they liked. She stared absently into the garden next door. Their old neighbour, for instance, still had the use of his legs, but what did he do with them? He watered plants and clattered noisily in the shed, but nothing of use. Nothing her dad had done.

She wouldn't have noticed otherwise, but that shed of his had been silent for half an hour. Jaz paused, her olive face crimped in confusion. Usually, her neighbour was in there all day. She tossed a sock back into the basket and drifted curiously to the fence. And that was when she saw him. The old man was lying in the doorway, legs splayed apart, his top half hidden from view.

Jaz moved instinctively. Gripping the fence, she hurled herself upwards and onto the other side. For months, she had dreaded something similar happening to her dad and now all that tension was uncoiling inside her. She pushed the door wide, fell to her knees and stared into her neighbour's thin, lined face.

"What the devil are you doing?" he barked.

Jaz jolted up with fright and hit the system boiler behind her. It clanged hollowly and, looking about her, she realised that this was no ordinary garden shed. There were tools, yes, and the windows were stained with grease and soot, but it was also the size of a small swimming pool and had a bench packed with complex electronic equipment that emitted a strange hum of power. The old man was fiddling busily beneath it and she wished she hadn't disturbed him.

"Sorry," she said, suddenly breathless. "I thought you were dead!"

Her neighbour's head tilted towards her and his blue-green eyes flashed with indignation. "It will take more than a leaking carburettor to finish me, young lady."

Jaz was stung. It wasn't her fault the old goat was still alive. "This looks like that junk yard down the road," she said, nodding at the mess. "What is it you're doing in here, anyway?"

With a groan of effort, her neighbour leant forward into a squatting position and Jaz had her first proper look at him. He must have been in his late sixties, with long, white hair greased smoothly back over an angular head. His clothes were just as odd. He was wearing a yellow tweed waistcoat, a white-collared shirt with a black ribbon tie and a pair of grey tartan trousers and elasticated boots. Jaz had never seen anyone dress in such a way before. Not even for charity.

"I'm a scientist," he said, and stretched painfully upright. He was taller than she had realised and his eyes were wide and angry and glared out of his gaunt face as though she had done something unspeakably foul. "I was just making repairs."

"To what?" asked Jaz, undeterred. "The Hadron Collider?"

The old man smarted fiercely. "I wouldn't go near anything so inaccurate. No, this is something of mine." He looked at the young woman with a new awareness, taking in her tip-tilted nose, yellow hoop earrings and untidy ponytail. "I'm the Doctor," he said and, interrogatively, "Who are you?"

Jaz was caught off-guard. Snapping out questions was usually something she did. "Jaz," she said.

"Like Glenn Miller?"

"No, just one–"

"I gave him his first trombone, you know," said the Doctor with sudden reminiscence. "He was fiddling about with a mandolin when I met him."

Jaz frowned bemusedly. The old man was clearly nuts. "Hold on, if this thing of yours needed repairs, it must've worked at some point," she reasoned, "and yet I haven't seen it before."

The Doctor snorted derisively. "You wouldn't see it," he said. "Humans aren't very observant. I've learned that much from being here."

"Being where?"

Perhaps, she wondered, he was from another country. Jaz had always wanted to go abroad – like Greece or the Gulf of Honduras – but the only time she could book foreign holidays was at the travel agency where she worked and even that was for other people.

"Ideally, it should be piloted by more than one person," he was saying now. "But you can't get the staff, you see."

For Jaz, the conversation was unravelling out of all comprehension. "Piloted?" she said. "You mean it can go places, then?"

"Oh yes, but not in the way that a car can."

"But it could get us to town?"

His pale face creased with amusement and pride. She seemed to have calmed him a little. "It could take us a lot further than that, my dear," he assured her. "Most ships do."

"Ships?"

"That travel through time and space," he said, as though it were obvious.

Jaz lifted her hands. "I'm standing in a garden shed," she said, "which is actually a spaceship?"

"Yes."

"This," she emphasised, drawing a circle with her finger. "A garden shed."

The old man seemed to take this as a personal affront. She had, after all, insulted the place once already. "It's my ship. It can look any way I want."

Jaz knew she should humour him. There was something, however, in his manner – that certainty, those incredulous, mocking eyes, the implication that it was she who was being ridiculous – which made her deeply irritated. Jasmine Driscoll could be patient and compassionate, and regularly was, right up until the moment that she felt her intelligence was being undermined.

"Explain how it works," she demanded and, even to her, this sounded like a playground dare.

The Doctor accepted this seriously. "Mainly, on Bernoulli's equation but, if you ask me, none of the Bernoulli boys really understood mathematics, though they could get a bit tetchy if you pointed it out to them." He leaned towards the door and clipped it closed. "It would be better if I showed you," he said pragmatically. "Explanations can be dull." He looked at her with curious expectation. "Where would you like to go?"

Jaz smiled, confused. "Where would I like to go?"

"Hmm." He seemed to consider this a reasonable offer. "We don't have to leave Shoreditch at all, but we could go somewhere else, if you'd like. Disneyland; the time of Boadicea; Disneyland in the time of Boadicea. Perhaps even Greece or the Gulf of Honduras."

He cocked a knowing eyebrow and Jaz wondered if he was joking, but something in his thin, stern face told her that he wasn't. He seemed to believe everything he had said. With a stir of nerves, she tried to remember whether she had mentioned her travel ambitions. She hadn't, of course. And yet, somehow, he knew of them already.

"All right, then," she relented, like an exhausted parent agreeing to play another game with a child. "Let's travel through time and space."

"Excellent!"

"I'd like to see Paris," she added, still humouring him.

"Priam's son, you mean?" The old man's mouth crimped contemplatively. "Well, I'll warn you, it gets rather bloody. Last time I was there, I almost got shot with an arrow!"

Jaz shook her head briskly and her ponytail danced. "I mean Paris, the city, in present times."

The Doctor shrugged. It made little difference to him. He took hold of a long, white lever and yanked it down with a stiffening squeak. Quite suddenly, Jaz heard something from outside. Somebody's lawn mower? An electric saw? Whatever it was, it seemed to be circling the shed, and getting louder too, like a dozen air compressor pipes that were broken and blasting and out of control. She felt a primitive desire to run.

"What's going on?" she shouted.

"The engine, my dear," the Doctor called back unconcernedly.

Jaz snatched a hold of the door handle. She was going to pull it open and get off this ghost train. But something, suddenly, tried to stop her. Something strong that gripped her shoulders and hauled her back and onto her heels. The shed, she just about realised, was tilting violently onto its side. Jaz let out a gasp as she was flung, weightless and weak, into the console desk behind her.

With a heavy, metal thud that surely must have cracked the Earth in two, the ship was suddenly still. The noise had stopped as well. Jaz felt herself swaying unsteadily, but couldn't remember the reason. A sheet of hot, thick steam passed before her eyes and she was reminded, stupidly, of a sauna she had used years earlier.

Maybe she was there again – at that silly spa – and maybe her mum would talk the same nonsense about quality time and how they will be fun, modern girlfriends and wouldn't stress anymore about parental responsibility or the swinging door of step-fathers. Perhaps, this time, Jaz wouldn't walk away for good.

Someone was speaking. A male voice, but not her dad's. It was older, colder and without the concern. Jaz opened her eyes blearily. The strange little scientist was looking at her with a detached interest, as one might stare into a glass tank at a rare breed of tropical fish.

"I've met a fair few humans," he said, "and most have been cynical, unimaginative and irrationally stubborn beings. You're … slightly less so."

Jaz heard the words, but she wasn't ready to untangle them. "Thanks?" she said, not quite knowing whether this was a compliment or not.

The Doctor nodded pompously, as though he himself were receiving praise. "We're here, by the way," he added inconsequentially.

They was certainly somewhere else. Jaz did not know how she was so sure, but it was a firm, frank conviction unlike any other she had ever felt. Whistling tunelessly and without spirit, the old man moved towards the door and flung it casually open. Jaz tottered forward and realised with relief that she could still walk. At this point, she wasn't taking anything for granted.

The garden, of course, was no longer there. Instead, a bright artificial light was beckoning them onwards. Jaz paused, unsure whether to leave the shed or not. Finally, after a moment to prepare herself – and, indeed, after many years of wanting desperately to see something other than her local high street and the pale glow of a computer screen – she smiled.

"Well," she said, "I've a feeling we're not in Shoreditch anymore."

The doors opened, music blared, and the Master spun on the spot flamboyantly. He had always enjoyed showing off and, in his view, the best thing to show off was power. The big, loud, obvious kind that nobody could deny and everyone could envy. He strutted forward like the whole world was his own private dancefloor – shameless, assured and drunk on funk. With an energetic bound, he slid across the console room and towards a vending machine.

"This song's about me!" he crowed. "I'm getting back to where I once belonged!"

Vincenzo Peruggia was standing warily off to the side. He had a tanned face and a smooth moustache and was dressed resplendently in a black dinner suit and shirt. Despite pulling off his disguise, however, he did not feel the control he usually did. All this talk of the coming days and sailing boats to the stars – it was the sort of thing written by Jules Verne or H.G. Wells. And such strange, clattering noise too. He gave his host a cold stare and the music was reluctantly terminated.

"That," said the Master with critical emphasis, "is the greatest band in history. Seriously, you have no taste."

Vincenzo Peruggia, however, wasn't in the mood for such discussions. "How did you know about the letters?"

"We still on that?" the Master complained. "You end up writing a memoir and I read it. Simples."

"And this …?"

"It's a machine that can reach the sky above and the times ahead. Sorted?" The Master turned to the console and began tapping the keyboard keenly. "I've always had difficulty driving these things. I could do with a SatNav, really."

None of this made sense to the Italian. "It can go places?"

His pilot paused at the keyboard. "Well, yeah," he said, "but not in the way a hansom can."

"But it could get us to town?"

The Master laughed. It was a stiff, unmelodious sound and strangely devoid of delight. "It can take us a little bit further than that," he said with scorn.

Peruggia decided to focus on matters of which he had some experience. "You want me to steal something for you."

The Master bit his lip hungrily and pulled a lever down hard. A stertorous breathing surrounded them and he punched the air victoriously. "Gets me every time," he enthused, then remembered what his new friend had said. "Stealing. Yes. It shouldn't be difficult for someone like you." He pressed a button and an image sprung up on the monitors above them. It was a photograph of himself beside a thin, blonde woman with delicate features. "In 2007, I am Prime Minister of Great Britain." He bobbed his head, grinning conceitedly. "I know, right? Amazing."

"It certainly is," said Peruggia, but the other did not discern the irony.

"I enslaved the planet, reversed the economy and dismantled the technology. Usual stuff. Now, though, I must focus on bigger things, not on some stupid resistance."

"Resistance?"

"Led by a woman, would you believe? Martha Jones. She's bringing hope to the people and are seen as heroes." The future Prime Minister smiled. "But I will put them in their place." He scratched his chin, where there had once been a beard, and began to explain his plan.

It was more than the Italian could ever have imagined.

Afterwards, the Master's face split into a self-satisfied smile. "Come on," he said, taking the lever again, "let's break the speed limit. Live a little." And, with that, there came the crunching, confident chords of 'All Right Now'.

Vincenzo Peruggia watched with amusement and awe as they entered into oblivion.

It was, to say the least, a surprise.

The rambunctious ride in the shed could have been simulated somehow, but no such trick could be responsible for this. Jaz stared with methodical concentration at her new surroundings. She had been transported, quite evidently, and in a way which was almost magical. And now she and the strange old man were standing in an auditorium with a wide linoleum floor, high ceilings and fluorescent lights. Most obviously, there were glass display cases positioned at intervals, though Jaz did not recognise anything that had been placed inside them.

"What is this?" she said with anxious inquiry. "The Louvre?"

The Doctor seemed to enjoy her astonishment. His ashen face had crinkled into a thin smile and he was watching her with paternal indulgence. "Not quite," he said, and pointed to the wall. "Out there is the Catacombs of Paris. An underground graveyard packed with the bones of six million people. Wall to wall skulls and not for the faint-hearted. We're towards the right, beneath the sixteenth arrondissement." He tugged at his lapels grandly. "This, my dear, is the Future Museum."

Jaz looked blank. "What's that?"

She was only asking to be polite. Really, if this was Paris, she wanted to see the Eiffel Tower or the river Seine. What was the point in visiting one of the world's most beautiful cities and spending the entire trip underground? She might as well be trapped in the Channel Tunnel.

The Doctor was disgruntled. "Good gracious me!" he said, his grey brows swerving together like two beetles in a fight. "Isn't it obvious? This museum exhibits artefacts from the future instead of the past." He began moving nimbly between the exhibits. "We jumped the queue, arriving this way, and we haven't had to bother with the gift shop either. All those tea-towels, notebooks, sticks of rock…" He shook his head disapprovingly. "You pay for the name with that sort of thing."

But Jaz wasn't interested in souvenirs. She was staring, dumbstruck, at this most unconventional of museums. "How come I haven't heard of it before?" was the first thing she wanted to know. "You'd think it would be world famous."

She wondered obscurely if this was an insult, but the old man seemed to have expected the remark. "Those hinges," he said, lifting a finger to the tall doors, "are fitted with an Automatic Memory Mangle. When you leave, you shall think you have seen only speculative ideas on the future. You've probably noticed your memory's a bit hazy already."

"Yeah, you're right," said Jaz, and touched her temple dubiously. "I can't … It's weird, but I can't even remember what my dad looks like."

The Doctor nodded, unsurprised. "It's a side effect," he said. "I have it too. This way, whatever invention people see cannot influence the world before it has been invented, therefore preventing paradoxes."

He spoke with such authority that Jaz trusted the scientist implicitly. It was as though she had known him for ages. Almost like a relative. He certainly had a grandfatherly look about him – but then, she supposed, that probably came with getting old. She got the feeling he could be irritable and curmudgeonly, and had been a bit already, but wasn't that the way with all granddads?

"This," he said, leading her to a flying car from Aston Airborne, "is what inspired me to start the place. Someone told me how the modern day wasn't what they had expected. I brought this back from the future to show them and, before long, I was putting other things with it too."

Jaz noticed a television mounted on the wall. "Why is there a telly?" she asked. "We have those already."

"Ah, that's a news report announcing the result of the 2071 republican referendum. It shall spell the end of the British monarchy as we know it."

Her expression was caught, somehow, between delight and horror. "Will it hold?"

"In a manner of speaking. After forty-six years, the monarchy will return under the honours system. King- and queen-ships will be awarded to those who represent Britain in some way internationally, with each incumbent keeping the title for ten years." He suddenly looked quite wistful. "People can get rid of things a little too hastily," he said, "and it isn't long before they want them back again."

Already, Jaz was distracted, scrutinizing a leaflet she had found on the floor. "What's Death Knell?"

The Doctor hesitated. "Well, it looks like a metal suitcase, but it's actually a super-weapon," he said carefully. "When it was replaced, it was put on display here, to much controversy."

"I bet," she said, only half-listening. She was looking at another exhibit now and grinned with embarrassment. "A headset," she read from the object label, "which allows two people to share dreams while asleep. A bit racy!"

The Doctor didn't approve of the humour. "Psychic phenomena isn't so unusual. If a person went near his past or future self, the proximity could make their minds entwine, with one asserting itself over the other."

"The way you talk," Jaz said with ironical disbelief, "you could make time-travel boring!"

The old man's mouth set sourly, and she wondered if she had overstepped the mark.

A young voice erupted behind them. "Hey, Mrs Carnegie," it sneered. "I think you might need this!"

The pair turned to see a short boy of around seven or eight years old with scrupulously tidy brown hair and designer clothes. A round, middle-aged woman came up beside him. Jaz felt sorry for her. The exhibit was for a 'hunger pill' which expanded in the stomach, removing any hunger pangs, and contracted a couple of hours later. It would, she read, threaten weight-loss empires, delight busy business-people and inspire corporations to eliminate lunch breaks among their labour workforces.

"We should keep moving," advised the Doctor. "There's a lot you'll want to see."

Jaz smiled. He seemed to treat these wonders with a sort of weary indifference, as one who lives beside the Statue of Liberty may become bored of the cooing tourists and flashing cameras. Did anything take him unawares? It was certainly not time-and-space machines – those domestic rockets that hurled people across temporal planes and international borders without even touching the sky. Jaz couldn't think of anything weirder than that. Maybe, she speculated, only aliens caught his attention, but did they exist? It was one of the more obvious questions to ask and she was surprised it had only just occurred to her.

"You'd like the Space Room," he said, as though she had already asked him. "It has the first extra-terrestrial ship, discovered by NASA in 2057. Most humans make a fuss of that." He smiled fondly. "Really, you are like dogs barking at your own reflection."

"I'm allowed to be a little impressed," said Jaz coolly. "Weren't you, when you first came here?"

His old face crumpled as he crossed the years. "Back then, there wasn't a museum to be seen," he recalled. "I had to have one built."

Jaz felt a giddy confusion. "Wait," she said, hands flat and fingers splayed in that way she always did when she wanted to get her facts in line. "The museum had to be here for you to have heard of it, but it couldn't be here if you hadn't built it. That's a paradox, surely?"

The Doctor looked amused, like a parent whose child had learned a new word. "No, no. Apparently, I shall live for a while in the early 1980s. Hence, in the past, my future has already happened. I will go on to build the place, but I didn't know that until after I had done it."

She considered this critically. "Sounds a bit … wibbley-wobbley," she concluded. "How long has it been here?"

"The question is," said the Doctor, "how long will it be here?"

Jaz made a face. She disliked it when people answered questions with more questions. It was like being criticised and corrected all at once. "Go on, then, how long?"

He was quite lofty about this. "Well, I haven't really checked, but it should be forever. In fact–" He would have continued, but a voice called out from behind him.

"Doctor!"

It belonged to a slim forty-something woman in a blue business suit with blonde hair pulled back into a tight bun. Jaz had the uneasy feeling that she was not to be crossed, but The Doctor seemed pleased to see her.

"Ah, Michelle," he said. "Jasmine, this is Ms Bellingham, the curator of the museum. She used to be my assistant, as it were, travelling around."

The woman was serious. "It helped," she recalled wryly, "when it came to my Futurism degree." She eyed Jaz with a curious aspect but, irritatingly, did not speak to her directly. "Your friend, I trust, is from the past, Doctor?"

"2005," he said with a knowing smile. "Still keen for visitors from all eras, Michelle?"

"Temporal diversity is very important," she said stiffly.

The Doctor shook his head with something like disgust. "Political correctness gone mad…"

A radio buzzed. "Excuse me," said Ms Bellingham and took it from her pocket. Jaz didn't catch the message, but it was obviously not good news. The curator's face tightened anxiously, like an actor who had forgotten her lines on opening night. She turned, faltering, to the room at large. "Could I have everyone's attention, please?" she called. "You must all remain in this room until further notice. We are in lock-down."

The Doctor was frowning. "What is it, Michelle?" he asked, but there was no time to help. No time, it seemed, for anything at all.

With a groan of resignation, the lights above them flickered once before plunging into an empty darkness.

The curator's voice came through coldly. "There's a robbery in progress, Doctor."

Things were going well.

The security guard had been too busy fetching coffee to witness their stylish arrival, and he only noticed something was wrong when his monitor snowballed. Now, the Master had rerouted all close circuit footage to his ship and was checking to see how many visitors were in the museum.

He had seen the place before – indeed, had life membership and was eligible for free parking and the quarterly magazine – but this was the first time he had tried to rob it and felt an almost sensual stir of excitement. A good thief, he had stolen everything from a nerve gas missile to the bodies of living people, but he had trouble accessing vaults and that was where Vincenzo Peruggia came in.

The Italian himself was at the door and getting restless. "I always act fast," he said with professional pride. He revealed a mask and draped it over his face – only the eyes were visible – and down to his neck. "Is our time now, mio amico?"

"Indeed it is," said his new partner smoothly. "I shall join you in twenty minutes and help you carry it back here."

Peruggia nodded. "And then, Mr Saxon, I will expect my letter. You had better not cheat me; I have quite an appetito for revenge."

"Oh, I'm aware of that, believe me, though I don't intend to betray you." The Master smiled with a sickening sincerity, and Peruggia decided that he must be a politician after all.

The Master sensed movement on the monitor and turned. The Doctor, he noticed, had slid into view. He recognised him at once, but only intuitively. It had been many years, and time had certainly changed his appearance. But then, of course, it had changed everything.

"This has just become a little more interesting," he murmured.

"How?" asked Peruggia. "Who is he?"

"Just an old friend," said the Master reflectively, and scratched his chin again. "Well, best friend. We even vowed to visit every star in the galaxy together. But you know how it is. You lose touch. Meet new people. Start wars." Brisk again, he tapped at the console busily. "Let's get the security boys back online. Least we can do is give him half a chance." His fingers finished with a flourish and he turned to the Italian with new purpose. "The plan is changing slightly."

Vincenzo Peruggia looked startled. "No!" he protested fiercely. "Who is this … this Doctor, you speak of? He a physician? He save lives?"

"Sometimes," said the Master lightly. "But, today, he's about to lose a few."

A faint hum, and the back-up generator summoned some light. It wasn't much. Just a few small bulbs glimmering shyly. A birthday cake would have been brighter. But it was better than nothing, Jaz decided, and at least they were able to see one another.

"What now?" she asked. As was usually the case, she was eager to do something, but wasn't sure what that something would be.

Ms Bellingham held up her smartphone. "Our cameras are back on now and they just caught this." It was an image of a man in black. "I will run it through the transparency scanner."

Jaz was not sure she could tolerate any more technology. "What's one of them?" she asked, suddenly out of her depth. This, she supposed, was how old people must feel in an age of e-mails, text messages and online banking. Even her dad had struggled with it at first, but he had lately taken to ordering groceries over the internet whenever she couldn't do the late night shop. It was the first sign he was becoming reclusive; something which concerned her still.

"A transparency scanner is a computer software program which scans an image and strips it of fabric, allowing us to see underneath," the Doctor explained. "But it isn't necessary. I recognise the black attire." His flinty eyes tightened distastefully, as though he had just sampled a plate of spoiled fish. "It's Vincenzo Peruggia. The only man to steal the Mona Lisa." He harrumphed with frustration. "This is what happens when you hire humans instead of mecha-guards."

Ms Bellingham was clearly embarrassed. "We do have one, but it's … an exhibit. People stand next to it and get their photograph taken."

With a hiss of static, there came a small, faraway voice of little confidence: "Michelle? I've tried calling it in, but I can't get through. I don't know what happened with the cameras, but he seems to be heading towards the west side of the museum."

The Doctor's brow darkened. "Why would he do that?"

"I'm going to have a look now," the voice added.

"Tony?" said Ms Bellingham worriedly, but it was no use. The radio wheezed, and she dropped her arm in defeat.

Jaz had quite forgotten the presence of anyone else, but was rudely reminded of it by the young voice from earlier. "Why are we still waiting?" Percy whined. He sounded as though he were chastising a waiter at a posh restaurant. The middle-aged woman, presumably his nanny, looked like she would rather be anywhere else but beside him.

"I don't know," she answered weakly and, in a poor attempt at optimism, "but I expect we can move on soon."

"Indeed," said the Doctor, overhearing the exchange. "From what I hear, I live to do some remarkable things. Like go fishing and cook an omelette."

Jaz could tell he was trying to distract the little boy, but the mention of food was a bad idea.

"I want an ice cream," he demanded. "I want one now!"

Mrs Carnegie seemed to summon every ounce of patience she had ever possessed. "Write something in that new book of yours," she suggested.

Moodily, the boy pulled out a Future Museum diary and began scribbling, and Jaz luxuriated in a moment of silence.

The Doctor, meanwhile, had turned to the curator with a renewed interest. "So, our man is heading west, hmm? Well, I doubt he's interested in the Domestic Room. It's full of high-dry machines and renewable carpets, and I shouldn't think he wants an anti-gravity nap either. Could he, per chance, be heading for the Military Room?"

"You mean…?"

He shrugged philosophically. "It was bound to happen one day."

"What is it?" asked Jaz, but the pair wouldn't be drawn. She stared at them with injured virtue. She had come across such condescension before. At work, for instance, whenever a snooty customer wanted to book a trip to the Aosta Valley and didn't expect her to know where it was.

The Doctor gave in. "Death Knell is in the Military Room," he revealed. "Stupid decision, really."

Behind them, the boy was arguing again and they had to talk louder themselves.

"Oh yes?" said Ms Bellingham, sounding like one of those serenely snobbish types in a Barbara Pym novel. "If you remember, the board enjoyed a robust exchange of views, and it was decided to host the exhibit by a vote of seven to five. Besides," she lifted a chin, all poise and stubborn self-belief, "our attendance rose by fourteen per cent in the first calendar year alone."

But the Doctor was unfazed by facts or how vigorously one might massage them. He moved to the door and Jaz joined him, a tingle of anticipation between her shoulders. Looking out, she expected to see Vincenzo Peruggia in the mask and with a gun in his grip, but there was nobody there. Just a corridor, like any other. Narrow, long and eerily empty.

Ms Bellingham produced a square device with an earbud.

Jaz smiled. "What's that? An iPod?"

"It's a Babble Booster," she said. "Amplifies sound, especially close conversations."

The Doctor took it cheerfully. "I think our young man may like this," he said with oily kindness and turned to offer it to Percy. But the boy wasn't there.

Jaz threw a panicked glance across the auditorium. The woman was missing too.

"Where are they?" she asked, but the Doctor was already alarmed.

He stepped into the corridor, listening intently through the device. Jaz kept behind him – feeling, with frustration, as though she were cowering, but she had to stay close to the wall or risk being seen.

Turning a tight corner, the old man came to an abrupt halt.

Jaz opened her mouth instinctively, but then remembered not to speak. Instead, she followed his gaze and found a figure at their feet.

It was a middle-aged woman with curly hair. Mrs Carnegie. Jaz fought back the impulse to cry out. The Doctor bent down, pressed his fingers to her pulse. Faint red marks encircled her neck. Someone, it seemed, had squeezed her dead.

With an effort, Jaz lifted her eyes and stared, squinting, down the corridor. All she could see were thick stretches of shadow. She moved forward, listening hard, her ears almost aching with the effort. Perhaps, she wondered, Peruggia had already taken Percy. He might even be dead, and they could tumble over his corpse right now. A restless desperation suddenly seized her and, before she even realised it, Jaz was running. Her footsteps were fast and heavy and she no longer cared about noise. At any moment, she knew, the intruder could curl around the corner and block her path. They might even collide. Despite this, she felt quite removed from the danger. Her concern for the boy – however wretched he was – had somehow numbed any inhibiting fear.

Finally, she halted, hesitant and breathless. If Percy had remained in the corridor, she would have passed him by now. He had to be somewhere else. Jaz ducked into the Culture Room and glanced anxiously around. A lightbulb, small and sickly yellow, glimmered weakly from the back. This room, she noticed, had a much homelier design: a couple of bright red sofas and a coffee table with a commemorative coronation mug of King George VIII. Facing it, a television was screening No Kids Allowed, a popular sitcom from the 2060s, and a tall curtain was draped over the wall where the window should have been. The kind of place, perhaps, where a boy might feel safe.

Jaz considered calling out his name, but it was no use. The sound system was playing a new song by The Beatles, created through the technological manipulation of melodies, lyrics and chord progressions from the band's back catalogue, and she couldn't compete. Confidently, knowing her footsteps would not be heard, Jaz peered over exhibits and peeked under tables. She imagined Percy fiddling with a do-it-yourself face-lifting kit or trying to administer a motion-tattoo but, frustratingly, he didn't seem to be anywhere. With this defeat, Jaz felt her chest tighten and, for the first time, realised that she was lost as well.

The song faded and the room fell to silence. Even the television programme had finished. She came to a bookcase stacked with post-apocalyptic survival sagas – best-sellers as humanity hoped to outlast a nuclear war – and paused. She had treaded on something. A diary, with the museum's logo embossed across the front. Like Percy's.

Jaz picked it up and flitted through the pages, her anxious eyes scanning the words. Yes, it was his; all scribbled notes about the thief and the weapon and the strange old man who was supposed to save them. If he had dropped this, she realised, then he must have been here, and Vincenzo Peruggia must have snatched him. Which meant that the Italian was close.

With a rasping whine, the door opened, and she jerked back beside the bookcase. Of course, she didn't move, but she saw something that did. A long, thin shadow, sliding slickly across the floor like a black snake. It was slow in that elegant way of all predators, and merged smoothly into the darkness surrounding it. Jaz had stopped breathing and didn't dare start again. The way things were going, she wouldn't get another chance, anyway. She heard a crunch of glass and the lightbulb blinked out. Jaz tensed, and waited to feel hot breath against her face and a blade across her throat.

But it didn't happen. Instead, there was a gentle tapping towards the door and the rustle of clothes as someone passed through it. Peruggia, it seemed, had left.

Though a natural cynic, Jaz felt a stir of hope rise up inside her and sucked in soft air. Maybe, she told herself, it was going to be all right. The thief had been alone, so he couldn't have found the boy yet either. She could continue her own search and find a way out of the museum as well.

Jaz stepped confidently forward and was about to move further when something gripped her arm.

And she gasped.

"I was wondering where you had got to."

A thin torchlight appeared and, behind it, the wizened face of the Doctor.

Jaz started. "Where were you?" she said, noticing Percy beside him, wearing a coat with built-in heating sensors.

"Behind the curtains," said the boy – and, just as casually, "A man in black killed Mrs Carnegie."

It occurred to Jaz that he may have been in shock. Or maybe he was just callous.

"You dropped this," she said damply, and handed him his book.

"And I was outside," said the Doctor, "though it's just as well I came in here, it's really quite interesting in its own way." He flashed the light idly on something behind Jaz. It was a newspaper, pinned to the wall, with a photograph of armed soldiers strutting through Downing Street.

Jaz noticed it and blanched. "What's this?" she asked, and began reading the article with earnest absorption.

It was dated 2007, and reported that the British Prime Minister, Harold Saxon, would order the killing of the American president and no less than ten percent of the world's population. She wondered, disbelievingly, whether this was a practical joke arranged by the staff of the museum. The Doctor, however, was also awed, and she knew it was true.

"There will be a resistance movement," she said with weak hope, but she couldn't even soothe herself. Her insides had twisted savagely with nausea.

The Dark Ages, it seemed, were coming again. A civilization which wasn't even worth the word. Her mind filled with images of people, weak and submissive and constitutionally scared. No democracy, no hope and no escape. She had to do something. She had to help them.

"Come on," said the old man quietly. "Things are bleak as it is. I found the security man – or, I should say, his body."

Even more bad news. With a heavy heart, Jaz followed the pair into the corridor. It was silent – though, of course, if the best thief in history was roaming around the place, would he really make that much noise?

She wished they could be in the auditorium again, before this had even happened, and continue staring incredulously at the exhibits. Come to that, she wanted to be back in her garden on Chesterton Road, putting the washing out. It was dull, yes, but refreshingly free of world slavery and time-travelling criminals.

"What do we do now?" she asked.

"We keep safe," was the old man's answer. "By now, Peruggia should've reached the Military Room and may even have accessed the vault. But he shall need to carry it back. It's heavy, so he will walk slowly." A finger pointed eastwards. "That's where the camera caught him. I'm going to block these corridors so he will be trapped between them."

"Blocked?"

"With a solidification spray."

Jaz smiled resignedly. "I'm not even going to ask this time."

Percy, however, was not so proud. "I want to know!" he demanded and, despite the trauma he had so recently endured, did seem interested.

"It's a sort of wall that's made from steam," the Doctor explained, and fished a hand in his pocket. "I snatched some from the Industry Room. Come the 2130s, all the builders will be using this." He revealed a slim, metal can and handed it to Percy. "Point it away from your face."

The boy studied the object cautiously, as one would observe a new bottle of insect repellent. Finally, he lifted it high, squeezed his eyes shut and pressed his finger purposefully on the nozzle. A jet of grey steam charged out of the can, discolouring the air and hanging languidly like a pea soup fog. Jaz and Percy watched with playful astonishment as the steam thickened into something stranger and more substantial. It reminded her of a rain-soaked window or a bathroom mirror after she had showered.

The Doctor reached forward. Instead of his fingers passing through and onto the other side, a faint clink was heard, as though he were touching a sheet of glass. He murmured amusement, and tapped out a brief staccato rhythm. It was hard as brick. Jaz smiled at this crotchety old man in a frock coat. Inside, she concluded, he was young in that whimsical, curious and eagerly joyful way that actual children weren't anymore. He was like Alice and Peter Pan and Jim Hawkins, but with a dash of Ebenezer Scrooge and the Wizard of Oz.

"Now, he can't pass," the old man declared with the satisfaction of someone who had just put up a shelf. Jaz certainly believed him. It was as though a wall, made entirely of ice, had been erected in the middle of the corridor. He turned towards the other direction, brows swooped determinedly together. "Right, let's head to the next corridor. With any luck, we won't even meet him."

But no sooner had he said this than the old man came to a jerking halt. And listened. Jaz did too, looking back into the gloom. Yes, there was something …

The sound of wheels. A trolley, perhaps. The weapon must indeed have been heavy. It was moving, however, with a restless urgency, as though the thief was eager to escape.

Jaz stiffened in anticipation. She could almost feel the rumble beneath her feet, like an oncoming express train hurtling along a track. She glanced at Percy reassuringly. "It will be okay," she said with a confidence she could not feel.

Why did people always say that? Had anyone ever believed it?

With a tap of footsteps and a rustling squeak, the trolley careered through the darkness. It was now uncomfortably close. For a moment, Jaz thought the wall had somehow dissolved and it hadn't stopped Vincenzo Peruggia at all. But then, as something scraped discordantly, it happened. The trolley slammed into the wall, lurched awkwardly to one side, and cast off its briefcase.

Which, as it lay flat on the floor, began to make noises of its own.

The thief paused grimly, heard its ominous hum. Wheels tinkling, he straightened the trolley again and thrust it into the wall. This time, with such force behind it, the wall broke in two and a slab smacked exhaustedly onto the other side.

The darkness seemed thinner now, and Jaz could make out a hand. It reached through the gap and grabbed a greedy hold of the Doctor's collar.

"Leave him!" she shrilled.

The man in black stepped forward, his mask hiding all emotion. Even more disconcertingly, his hand was trailing to a pocket. With a clink of cold metal, he pulled out a gun.

The Doctor, however, was unruffled. "Now, look here, young man," he began, but the weapon raised itself towards him. His old eyes flashed indignantly, as if he had just heard a teenager swear. "You won't get anywhere waving that thing around."

Jaz couldn't restrain herself. "Yeah, I bet you're nothing without the gun!"

This was not quite true, of course. He had the suitcase, and it was now ringing out a series of slow, assertive chimes.

"That's the Death Knell," said the old man gravelly. "You've triggered it, you fool!" He paused, helpless. "We must find somewhere quiet, where the sound can't kill us. Now!"

Their captor, however, seemed to luxuriate in the call of Armageddon. Indeed, it had a strangely languid elegance, like church bells in the countryside, evoking a peace it would soon destroy.

The Doctor was forthright. "We're all going to die if we don't move."

"Not all of us," was the bland reply.

Jaz wished she hadn't heard that. "You're going to kill us?" she pursued. "Even the kid?"

Despite the mask, the man's confusion was clear to see. "What kid?"

The other two could have asked themselves the same question. No one, they realised, was lurking behind them. For the second time that day, Percy had vanished.

Jaz felt as though her very soul had been sucked out. The odds of finding the boy and hiding them all in time were precisely none.

But then, impossibly, he was there again – leaping from the side, and the ruins of the wall, brandishing the solidification spray. He aimed it high, pressed it hard, and spurted steam into the man's eyes. Even the mask was no use against it.

The thief stepped back, dazed. But Percy didn't stop there. He pushed himself forward, hands waving, fighting for the gun – which, unfortunately, was too much, as it cracked conclusively through the corridor.

Jaz froze, the breath caught in her throat.

The gunman stiffened. Blood began seeping from his right shoulder, his hand pressed stickily against it. Panting softly and, it seemed, with bitter incredulity, he sank to his knees and onto his side.

Jaz crept closer, cautious but concerned, and fumbled for his pulse.

"What happened?" asked a woman's voice. "What's going on?"

It was Ms Bellingham.

"Quickly," instructed The Doctor. "Get the boy somewhere quiet."

The curator snatched Percy's hand. "Come on!" she cried.

But Percy was having none of it. He pulled himself free and ran off down the corridor.

Jaz bent over the body. With a flourish, she pulled off the mask. But the man underneath it was not who she had expected to see.

"What's wrong?" came the Doctor's voice.

She hesitated. "Give me your coat. We need to stop the bleeding."

The Doctor drew level, saw the thief's face.

"Do it!" Jaz commanded. "It doesn't matter who he is."

She wanted to believe this, but it was much too hard. The man lying before them was not the thief they had seen in the image earlier. This, she realised with a cold shock, was Harold Saxon.

Jaz took the Doctor's coat, pressed it against the wound, and wondered how many breaths he had left. Her mind was reeling. This had been an accident, obviously, but would the court agree? Percy was young and innocent and had fought in self-defence. But then, who knew what laws existed in this place? She wasn't even sure it existed itself. With a sort of desperate horror, Jaz kept on pressing the wound. She should have acted fasted, she realised, tormented. Things should not have ended this way.

The chimes echoed on, but she could barely hear them now. The image of the man's face seemed to have burned itself onto her retinas, and all she could feel was a cold hand on her shoulder as the Doctor guided her up.

"We need to get him somewhere too," she said.

"No," said the Doctor gently. "We can't help people like him."

In her weakened state, Jaz didn't question his piety, but allowed herself to be led away. They entered a room where a large, square vault stood grandly in the middle. The chimes were slower now, merging into one another to make a long, weary groan. It was as though a clock was ticking down towards their doom.

The door was ajar and the Doctor pulled it wide. Jaz wasn't expecting to see anyone else and, peering inside, jerked with surprise. A tall man was sitting, hunched, in the vault. He was wearing a sack suit and a Raglan overcoat and, without the mask, was only recognisable from his general height and shape. It was Peruggia, certainly, and he seemed just as anxious as they were.

The Doctor's face was lit with a friendly smile. "May we join you?" he asked politely and, without waiting for an answer, clambered inside. "Glad to meet you at last. I'm afraid we had to hide when you were wandering around the Culture Room earlier."

Jaz pulled the door heavily closed and turned to face the Italian. She was so weary, by this point, that she couldn't summon the energy to be scared. "That was you?"

"I couldn't find this vault," he admitted despondently. "Once I did, and got that suitcase, my so-called partner insisted we go back separately. I don't think he trusted me with it, as a criminal." Vincenzo Peruggia smiled weakly, as though only now embarrassed by his profession, despite being its very finest exponent.

"And I'm guessing, to avert our attention, he dressed himself in your clothes while you broke into the vault?"

The thief nodded and Jaz, sitting back against the wall, blew out an exhausted sigh. Maybe it was the shock of seeing someone shot, or maybe it was this approximation of a nuclear warning, but Jaz felt weak and her head was heavy. It was like she was five years old again and had stayed up passed her bedtime. Her mum was always letting her do that. Jaz had thought it was a reward for being a good girl. She later learned it was because her mum could not be bothered to take her upstairs and read her a story. Perhaps she was there again, on the couch, and had fallen asleep in front of the television, and this whole day was a surreal dream.

A hard object hit the roof of the vault and she jerked upright in alarm. She remembered, with something like surprise, that they were still underground. Above them, twenty metres of stone and dirt was being unsettled. Jaz tried to focus on something which didn't involve being trapped in a vault with a notorious criminal and buried under a small rock quarry.

"I hope Michelle is all right," The Doctor murmured, ignoring the noise.

Jaz could tell he was worried. "I'm sure she will be," she said, still staring at the ceiling. "After all, she survived her travels with you."

The old man, however, was uneasy. "Just about," he said. "She saw things, you see. Traumatic things. Changed her, really, seeing what becomes of the world, as it would with any human."

Jaz could certainly understand that. She could still see that newspaper now.

"Running this place is how she copes with it," he went on. "She has her own version of the future here."

Jaz looked at him levelly. She had forgotten the Italian was even there. "And how do you cope with it?"

The Doctor suddenly sounded vague. "I'm not sure I do," he confessed. "By helping people, I suppose."

"You always try to do that?"

"I could ask you the same thing," he said with wry amusement. "You care for your father; you tried to help me in the shed; Percy too, and that fellow out there. You even want to be a paramedic."

Jaz could have asked him how he knew this, but decided weirder things had happened already.

"I think," he reflected, "we like to feel needed."

"We're certainly needed now," she agreed. "I just wish we knew what it was about."

This spiked the scientist's interest. "Well, it might have something to do with that political upheaval we read about. I haven't known of it till now, you see. Though how time-travel got to be involved, I don't know. Yet."

Outside, the bells had ceased, but the rocks still fell. The vault was half-buried and soil covered the linoleum like carpet. The Doctor passed stiffly through the room, somehow managing to avoid being hit. He seemed tired, crestfallen, and Jaz remembered that he had founded the museum. This will not have been his favourite visit. The ceiling rumbled again and the three of them raised their heads with bleak anticipation. It was even more frightening than the chimes.

Jaz searched the corridor. Harold Saxon's recumbent figure was nowhere to be seen. She wondered whether he had found shelter or if the siren had caught him out.

The Doctor appeared behind her. In the lines of his forehead, she read his next few words. "I've found Michelle … Ms Bellingham," he said quietly. In the distance, there came a crash, as another ceiling fell fatally through. "Her knees were scuffed, as though she had fallen." His voice was hard, unemotional. "She had been made to hear the bells."

"Murder?"

Jaz did not know what to say. The usual platitudes seemed somehow unsuitable. Cracks cut through the ceiling, and the Doctor moved off with the purposefulness men had in those old British war films she had watched with her dad. It looked comically absurd, though it really shouldn't have been at all.

"Wait!" she called and, with a bound, drew alongside him. "We need to find Percy."

More rocks dropped, closer now.

"I haven't seen him. He must be somewhere under this mess." Jaz was shocked at his dismissiveness. "All that's bothering me now is my ship."

"Ship?" Jaz echoed. She had forgotten it completely. "What's the matter with it?"

"It's gone." They turned down another corridor, passing rooms of rubble.

"If Percy's gone," she argued, trying to stay calm, "and so is your ship, then maybe the two left together."

Reluctantly, the Doctor agreed that this was a possibility. "He may have gone in there to hide," he allowed. "The ship's sensors could have detected him entering and automatically dematerialised."

As he spoke, Jaz realised something. Ms Bellingham had been pushed to the ground, but the Prime Minister couldn't have done it. Even if he was still alive, he was too weak. Similarly, Peruggia had been in the vault. Both men, then, had alibis. The only other person…

"This way!" cried the Italian, gliding ahead, and they followed him through another corridor.

At the corner, they stopped, and a look of surprise came into the old man's eyes.

It was the garden shed. His ship.

"How did it get here?" Jaz asked bewilderedly.

But they didn't have time for such questions while the roof was falling asunder.

"Quickly!" instructed The Doctor and, as rocks crashed around them, they ran into the ship.

The lights welcomed them warmly. Jaz had never been so pleased to see anything in her whole life. The Doctor strode to the console and tapped it affectionately, as one might pat a dog.

"So, Percy didn't take this ship," said Jaz, relieved. "We were wrong."

The Doctor, however, was looking grim. "Oh, he took it, all right," he said. "Think about it." He turned abruptly and Jaz was reminded of her old headmaster at Coal Hill School. "Three people have been killed, and we thought the man in black had done it. Percy even said so. But, if you recall, he had heard me mention Peruggia, and how he was wearing black. He knew, then, just what to say."

Jaz had begun to wonder the same thing. "Percy was responsible," she said, her voice hollow. Out loud, it sounded outrageous. He was, after all, just a boy.

"The siren went off," the Doctor continued, "and he fled in this ship. As you would expect, over time, he ruminated on his crimes, and began to see himself as a ruthless murderer. And so he became one. With no more humanity holding him back, he went on to do even more evil things. Eventually, he became the very man he had killed."

"The Prime Minister?" said Jaz, her mind clouding with doubt. "That's who Percy grows up to be?"

"That isn't the least of it," The Doctor lamented. "He wanted to keep his power, but needed to defeat a resistance which had been mounted against him. He was also in the room, you will recall, when I mentioned the Death Knell."

Despite her own misgivings, things were becoming clearer to Jaz. "He made notes," she said, remembering the boy's boredom, "in that diary of his. I saw them myself."

"Quite. Well, as an adult, and still in possession of this ship, he collected Peruggia and brought him here to steal the weapon to use against the rebels. This spot here is where they landed."

He looked fondly at his home, now it was centuries older than the last time he had seen it.

Jaz turned to the Italian thoughtfully. "Is this true?"

"I only know that he found me, mia ragazza, and he was a most curious man."

"He was indeed," said the Doctor, rubbing his brow sorrowfully. "If it wasn't for the Automatic Memory Mangle, I would have recognised him immediately. You see, he and I grew up together. We are, I'm afraid, old enemies. He is known as the Master."

The young woman stared at him in shock. "That's … news," she managed.

"Of course," continued The Doctor, "his younger self left in such a hurry, he hadn't noted the part where someone else was killed. Nor did he realise the urgency to do so. The instinct to kill, however, would leave its own mark."

Jaz was earnest. "Earlier, you said how two minds can become one, or something, when you meet your other self. You reckon, then, that the presence of the older Percy could have caused the younger one to adopt the same homicidal tendencies?"

"Certainly I do," said the Doctor, and his voice was one of frustration and regret.

Vincenzo Peruggia joined in. "You mean to say, signore, he was murderous, because his older self was murderous, and that was only because his younger self was murderous?"

"Hmm," the old man concurred.

"But why push Ms Bellingham and force her to hear the siren?"

"To test the weapon. He understood what his older self was up to. And the guard was killed because he was about to search the museum and would have noticed that there were two identical ships here. He did the same to his nanny because–"

"Because," finished Jaz heavily, "she wouldn't fetch him an ice cream." She paused, disgusted by such a trivial motive. "I thought, at first, the shot had been accidental, but it couldn't have been."

"It was fate and fatal," said The Doctor wryly. "Quite literally, he had himself killed. What we call in time travel a rookie mistake."

Jaz looked away uncomfortably. The old man could be ruthless himself, and it wasn't something she appreciated. She thought sorrowfully of those who had passed. Despite what that memory widget would do, Jaz didn't think she could forget such an extraordinary day.

It was Peruggia who spoke first. Being a criminal himself, he may not have understood the idea of respectful silences. "Doctor," he said, "can I go home? On this occasion, at least, I have not succeeded in the robbery, which wasn't even my idea."

Jaz did not approve, and she was about to say so, but The Doctor accepted the request without persuasion. Perhaps he suspected how vigorous it might be. "For better or worse," he said, "I try to avoid changing history, and you have a little more of it left to see." He turned to Jaz and his eyes glimmered shrewdly. "While we're in early twentieth century Paris, we could have a look around ourselves. You always did want to visit the place, and I can get you back home to your father before you even left. What could be better than seeing the City of Light in the Belle Époque, its golden age? With Moulin Rouge, the Ritz Paris and Art Nouveau?"

"Nothing," Jaz agreed but, despite her eagerness to see the place, something troubled her still. "What with everything that's happened here, though, would it be right, do you think? Enjoying ourselves like that?"

The Doctor seemed astonished, and she wondered how a human could be so thoughtless. But then, of course, she wasn't even sure he was human. Few things would surprise her, at this point. He looked at her, however, with a delicacy and understanding which seemed to confirm what he had said in the vault. This old man – alien or not – did indeed want to help others. He just hadn't got the hang of it yet.

"Percy tried to ruin lives," he said quietly, "and even ended some. The best thing we can do, in response, is live our own."

Jaz nodded philosophically and decided she would light a candle at the nearest church for everyone she had met that day. "Will we have time to visit Notre Dame?" she asked.

The Doctor smiled. "My dear, with this ship, we have time for everything."

And, as a wheezing, groaning sound encircled them, they left the Future Museum behind.

THE END