“I thought they would have wanted more time to study the consequences of their changes,” Alb said. “They can’t have learnt much in that short a period, spending just a few minutes in that timeline every century.”

  “Oh, the time travellers stayed there for months, even years, of their Personal Time,” Cassique said. When he saw their confusion, he swiftly elaborated. “When we enter the past, we experience time the same way that people of the period we’re in experience it. If we stay there for ten years, we age ten years. We call the time we spend in a past timeline, Personal Time. But only a fraction of that passes in what we refer to as Present Time. So if we spend a month of Personal Time on a mission in the past, only a few minutes of Present Time will have elapsed when we return.”

  “That’s a head-scratcher,” Beta D muttered, “but I think I get it. So, with the Columbus example, let’s pretend for simplicity’s sake that the team had limited their observations to three centuries, and visited that timeline for a month in each century to check that everything was going OK. For the people in that timeline, three hundred years would have passed. For the Fixers, three months would have passed, and that’s how much they’d have aged. But here in the present, only three days would have ticked by for everybody else. Is that about the sum of it?”

  “It’s never that neat,” Cassique smiled, “but yes, that basically sums it all up, relatively speaking.” He winked at Alb, whose theories had been central to the unlocking of the portals of time, then continued with his account of time travel’s early years. “Experimental trips to the past ran around the clock, one mission after another, headed by different teams. There were so many time periods that Historians wanted to tinker with. Some wanted to go back only a few decades or centuries to carry out controlled experiments, looking at what would happen if you made very minor changes in a very specific field, while others were interested in going back a few thousand years and making sweeping changes which would affect the whole of civilisation. The Historians were keen to squeeze in as many missions as possible, as fast as they could, as they knew the clock was ticking and the Time Hole would collapse at some point in the not-too-distant future.”

  “You’re sure it won’t remain open indefinitely?” Alb interrupted.

  “One hundred percent positive,” Cassique said. “Father can hasten its closure – he plans to shut it down before it closes naturally, once we’ve corrected all the timelines – but he’s never found a way to bolster its walls and keep it open for longer. He estimated, a few years after the explosion, that we had approximately two centuries of Present Time to play with. Somewhere around that point, as closely as he could predict, the strain on the sides of the Time Hole would force it to close.”

  “Strain?” Alb was focussed intently on Cassique. “Where does this strain come from?”

  “From time,” Cassique answered. “The Hole penetrates time, clean through to 3000BC, but only in one spot. It’s like… You’ve heard the story of Moses?”

  Alb blinked, thrown by the sudden change. “Of course.”

  “I think so,” Beta D said, less certainly. “Wasn’t he the guy in those twentieth century movies, with the beard and the long hair?”

  “Those were actors,” Cassique told him. “The real Moses – I mean the mythical one, as he didn’t actually exist – was a man who led a race of people known as the Israelites out of a place called Egypt, where they were slaves.”

  “He was kind of like Spartacus?” Beta D asked.

  “Kind of,” Cassique agreed, ignoring the guffaw of disbelief from Alb. “One of the things he supposedly did, while leading his people to safety, was part a sea. Legend has it he lifted his arms or struck the sand or something, and a path opened up in the sea in front of them, and that was how they escaped.”

  “I remember now,” Beta D said.

  “Oh, you do, do you?” Alb shook his head despairingly. “If this is the face of my future, I’m glad you took me when you did.”

  “Yeah, I know it,” Beta D went on, ignoring Alb’s friendly jibes. “That was the one where the sea divided. There were walls of waves to either side, held back by magic, but the walls fell when the baddies followed, and they all got drowned. I saw that when I was a nipper. A great old film.”

  “Well, I haven’t seen the movie,” Cassique said, “but roughly speaking that’s what the hole through time is like. It divides the temporal sea but only for a while. All the time the walls are coming under immense pressure from the waves. One day the walls will crumble, and the sea of time will rush back in to fill the gap, and everything will be the same as it was before. You understand now?”

  “Sure,” Beta D said.

  “Yes,” Alb responded.

  Cassique paused once more as he contemplated the next part of the story. “For a few decades we thought all was good. We had a hole in time which we could pass through, a couple of centuries to play around with it, and no problems so long as we crossed our i’s and dotted our t’s whenever we were done testing any given timeline, to ensure the changes were negated and couldn’t come back to haunt us when the Time Hole shut.”

  “But there were complications?” Alb guessed.

  “Dos, yes,” Cassique groaned. He passed a hand over his eyes, shook his head grimly and pressed on. “We began to notice, as we went about our business in the past, that things were different in certain eras and places. History had changed. We’d go back to a certain date to experiment with an Einstein or a Beta D and find they weren’t the way they should be, that Einstein hadn’t come up with the theory of relativity when he should have, or Beta D had killed himself after his accident with a computer game. Stuff like that.

  “The past had changed in many places and no longer corresponded with our original history records. The more we travelled back and looked around, the more discrepancies we found, people out of synchronisation with their histories. The Egyptians hadn’t built the pyramids. The Confederates won the American Civil War. The apple didn’t drop on Newton, even figuratively speaking. Shakespeare got a job on a farm and never wrote any plays. James Dean survived his crash and went on to make more than a hundred films that were so mediocre, nobody cared to watch the first few good ones that he’d starred in. And so on.

  “We thought our tinkering was to blame, that this had happened because of changes we’d made during our experiments, that we hadn’t rectified them as neatly as we’d assumed. We went over and over the records of our trips to the past, looking for the slips that we must have missed, but there weren’t any. We’d been as clean and efficient as we’d believed. The changes we’d made weren’t the root cause of the fractured past.

  “Then we thought, maybe it was a result of people from our future, travelling back as we were, and their messing about in the past had resulted in the… well, the mess.”

  “That couldn’t happen,” Alb said shortly. “No, impossible.” He shook his head vehemently. “A time hole could only stretch back from the present in which it had been created. The future can’t exist at the same time as the present. Unless they had come back in time, to your time, through one time hole, and opened another in your present…”

  “No, you were right first time,” Cassique said. “Our future selves had nothing to do with the scrambled past. Father could find no evidence of a time hole from the future into our present and dismissed the notion. Besides, the only being on Earth who fully understood how to create such a time hole was Father, and he’d determined never to open another one again.

  “So, we studied the matter further. We went through all the options one by one, discounting alien influences, future intrusions, parallel universe theories, and wrongly recorded historical accounts — we thought maybe the records that had passed down to us had been rewritten centuries before, by one oppressive regime or another. We were thorough in our search. We couldn’t afford to dismiss any possibility, no matter how crazy or improbable it seemed. In the end, when we’d discounted everything else, it turned out the answer was embarrassingly simple.

  “The explosion itself was the source of the disruptions.” He beamed at the other two, who simply stared at him blankly. “The explosion changed history,” he said, trying to make them understand. “The shock waves it created swept back through time and altered the past.”

  “In what way?” Alb asked.

  “In hundreds of thousands of ways,” Cassique answered. “It didn’t change the entire past, only sections of it. You can think of it much the same as the damage inflicted on a group of people who are standing on the perimeter of an ordinary bomb blast. The blast won’t kill all the bystanders, but it can damage body parts, puncture eardrums, blind eyes, rip off a limb or two here and there.

  “The time explosion wreaked a similar kind of damage. The shock waves didn’t destroy the past – there’d be no hope for us if they had – but they wounded it. They randomly changed certain events and people. In this new, shaken past, the Russians were first to the moon. The British fell to the Spanish Armada. Ronald Reagan won an Oscar and stayed in movies. Bill Gates didn’t quit Harvard or found Microsoft. You follow?”

  Beta D pulled at an earlobe, uncertainly. He shot Alb a questioning glance, but the greatest mind of its time was looking inward as it mulled the matter over.

  “History has changed?” Beta D finally asked.

  “Parts of it, yes,” Cassique said.

  “Only parts?” Beta D pushed. “Surely, if one block goes, all the others must tumble too.”

  “Not blocks,” Cassique said. “Tabs.”

  “Tabs, blocks, what’s the…” Beta D winced. “Oh, hold on…”

  “Tabs exist independently of one another,” Cassique finished the thought for him. “When Father opened the Time Hole, the past experienced the aftershocks simultaneously, which basically opened up hundreds of thousands of different time tabs, and history is unfolding independently in each of those tabs, but at the same time as in every other tab, and in isolation from them.

  “Let’s take two different leaders in time,” Cassique said, trying to make it easy for his charges. “Julius Caesar and…” He’d been about to say Donald Trump, but Alb would have no idea who that was, and the explanations would have taken too long and taxed his credulity. “Otto von Bismarck. When the Time Hole opened, one of the tweaks imposed on history was that Caesar wasn’t assassinated. He heeded his wife’s warning, stayed at home that day and lived another twenty years. Nearly nineteen hundred years later, a teenaged Bismarck cut his foot on a nail, it got infected, and he died.

  “Both of those changes had seismic, far-reaching consequences, and changed the future of their timelines indefinitely, but from our viewpoint they happened at the same time. Hundreds of thousands of alternate timelines were created, which means hundreds of thousands of different histories are unfolding even now beyond the walls of our Time Hole, but their points of origin remain embedded in our past. Thus, if we go to the 1840s to push young Otto out of the way of the nail that was going to seal his fate, we find a world where Julius Caesar was killed, and where the Egyptians did build the pyramids, and where Montezuma didn’t have Cortés beheaded.”

  “History has been punctured in hundreds of thousands of different points,” Alb murmured, “but all the punctures were inflicted at the same moment, so the earlier changes have no influence on the time periods where the later changes are taking place.”

  “Exactly,” Cassique nodded. “The changes haven’t affected our present and won’t until the Time Hole closes. They’ve had knock-on consequences, and created their own parallel versions of history, but none of those other-tab-pasts can disturb our present world so long as the Hole is open.”

  “Then it’s possible to correct things?” Alb asked.

  “Absolutely, if we can isolate all the discrepancies and fix them,” Cassique said. “That’s why we’ve been kidnapping people and engineering events to suit our own needs. It’s not hard to fix any given hiccup in the past, but when you consider the parts as a whole… when you take the hundreds of thousands of blemishes into account… It’s like a massive jigsaw puzzle, the biggest the world has ever seen, whose pieces are scattered across almost six thousand years.

  “First you need to identify all the pieces, then you have to slot them together correctly. It’s a mammoth task. We’ve been delicately balanced on a knife’s edge for a hundred and seventy-three years now, aware that one simple mistake could destroy us all, having to rush to beat the unavoidable closure of the Time Hole. It looked for a long time like we weren’t going to make it, that there were too many flaws for us to fix, but Father bred more Fixers, and we increased our work rate, and slowly, gradually, we’ve come out on top of the situation. It’s been hard, it’s been exhausting, but we’ve done it. Almost.”

  “The flaws,” Alb said. “How do you recognise them?”

  “We have complete history records,” Cassique told him. “Father has access to every news report and historical record ever digitalised. He’s merged them all to create a super-history which lists every moment of humanity’s development and progress through the ages. It’s the most accurate, all-comprehensive file of its type ever compiled. With that to guide us, we go back in time, compare what we find with what should be, and make any necessary changes.”

  “But the records could be wrong,” Alb said. “History is often recorded from a position of bias. Generals exaggerate, conquerors rewrite the past, thieves take the credit for others’ successes. How can you be sure that your record of the past is the correct one?”

  “It doesn’t have to be a hundred percent accurate,” Cassique said. “So long as it generally corresponds, it’ll be fine. For instance, in your later life you’re credited with inventing the theory of relativity. As far as we know, that was all your own work, and you really were the greatest mind of your time. But you might not have been. Perhaps you swiped the idea from a penniless student, then slit his or her throat.”

  “I would never –” Alb started to protest loudly.

  “I’m not suggesting you would,” Cassique calmed him. “I’m merely using it to illustrate a point. And the point is, if you did steal it, if it wasn’t your theory, so what? History has credited the breakthrough to you. Billions of people came to know your name and understand something – in most cases a very little something – of your theory, but how many knew you? How many people met you or spent time with you or knew your favourite joke or how you ate or how you treated your friends and relatives?” Cassique shrugged. “It doesn’t matter. You could be a saint, a son of a bitch, or one of the masses in between. Nobody knows, nobody cares, and it doesn’t make a jot of difference.

  “The everyday world exists separately to that of time and history,” Cassique continued. “People matter in life, of course, but history takes little notice of them. Moses didn’t exist, so he didn’t part a sea or bring the Commandments down the mountain, but he did in the historical records, and thousands of years on from when he allegedly lived and died, that’s all that really matters, isn’t it? The myth is the reality, as far as history is concerned.

  “Maybe Mozart wasn’t as brilliant a prodigy as reported, but we all know him as a boy-wonder. When people think of him, they think of the six-year-old entertaining the kings and queens of Europe. In reality, maybe he did and maybe he didn’t, but historically he most definitely did, and when the Time Hole closes, that’s the only truth that’s going to matter. That’s all we need to get right. The minutiae of life, the everyday world of eating and drinking and breathing and sleeping… irrelevant.”

  “You think so?” Alb asked.

  “How could it be otherwise?” Cassique said. “A person’s actions are lost to reality within seconds. Their words and deeds are forgotten and confused within minutes. Look at us three — if we were asked, an hour from now, to relate this conversation verbatim, how close do you think our accounts would match?”

  “You have a point,” Alb admitted.

  “History is what the stories have made it,” Cassique said bluntly. “Nero might not have fiddled while Rome burned, but so long as legend says he did, he did, and so long as we get the legends right, so long as we can fix the past to fit the style of the stories, we’ll be OK when the Time Hole collapses. If we control the story of the past, and make sure it matches the story that was told before we punched a hole through time, we’ll control reality. And that’s not my view — it’s history’s.”

  They’d been talking for what seemed like forever. Cassique had never engaged in a conversation this long before. Communication was no longer a skill or a requisite in the twenty-ninth century. Father answered questions quickly, in the manner of all binary mechanisms, and the humans of the time weren’t much different. As far as they were concerned, talk slowed action down and was to be avoided whenever possible. Cassique rubbed his hands over his unusually dry throat and ordered a honey-based drink which he sipped gingerly.

  Alb and Beta D had moved their chairs over to a corner and were discussing the ramifications of time travel as it had been outlined to them. Cassique could see them drawing up a mental list of further questions and groaned quietly. The sun was down for the night and there was nothing he wanted more than to sleep, but he supposed he might as well stay up and see the talks through. He didn’t want to be facing the pair and their questions first thing in the morning with a groggy head and bleary eyes.

  When Beta D and Alb were ready, they drew their chairs back towards the couch, where Cassique was still sitting, and the interrogation resumed.