"...there are hundreds, if not thousands, of meaningfully-distinct universes infected by anomalous particles every day, representing an almost indescribably small percentage of the central reality belt. These rogue elements are the fundamental building-blocks that define the 'survival of the fittest' when it comes to laws of physics. The earliest and perhaps the most famous example of one such event was first described by Petrowski et al from the Castillo research group of the Safrin Scientific consortium almost sixty years ago, in which a small group of detectably-close realities were infected in the early twenty-first century.

Anomalous particle attacks occur, of course, randomly wherever they can – in this case spontaneously because of the high energy levels in an S552 "Atomic Vice" accelerator in London, the schematics of which were analysed to be identical to one operating long ago in our own world. Whilst the Castillo group produced breakthroughs when it came to identifying what made these realities fail, it took another twenty nine years before the mechanism of law-making was identified and isolated, and numerous incremental efforts were mounted to begin to understand the process of physical law-creation from afar. Whilst better models have since arisen, the early Atomic Vice study remains relevant to this day, notably referenced as far afield as being referenced in pop-group EB's third album title 'Final Homonyms'." – extract of 'The unseen destroyer: A history of the Darwinian multiverse'.

"Navari, hold up. Where are you going? Navari!"

She took the stairs fast, as fast as she dared with shoes soaking. "Come on Hortez! If we can't stop the evacuation then we need to find them first."

"Us versus the British?"

"If we want them alive, we go now." She glared. "The only thing we can do now is hope we get to them before the CTC." She disappeared out of view. "You know Schofield, he'll fight."

Surely Raynes would know what was coming, she thought to herself. Raynes would prepare. She knew the people they hunted would realize what comes after a crisis like this, and would know that in a goddamn university full of students the evacuation was the first thing that would be done as soon as possible. And she was determined she'd be there. when they were caught.

Through stairwell windows she caught fragments of the teams moving in to begin securing the area around the extended university complex. Sirens blared. Where would Raynes go? How would I try to escape from CTC if I were them? And then there was the one unanswered question. Who's blood was it by the missing doors, and why did any trace of it go so cold so fast? She took the stairs two at a time now and rushed past the gigantic reception desk just as she saw CTC officers taking positions across the street. Something came to her then, a thought which was insanity but one she couldn't dismiss. This is what it would look like if there was an apocalypse. Cars stationary, abandoned, the riot-heavy ballistics across the street, military piling in, the foyer of police tape would look just like that-

She found herself slammed to the floor, physically thrown face-first and gasping for air as the entire Huxley building vibrated, shook and flexed with the earthquake whoof of pressure. It passed through her in an instant, a megalithic crushing force that in that moment seemed to meander and threaten to burst her skull before it moved onwards to blast out the windows into glitter and catapult her skidding and tumbling across the marble. The room roared with it, staggered and settled again. Some people saw it from up close on the top campus floors; the brief puff of smoke around the engineering building that smouldered and then ruptured in a moment when the ground and its hundreds of tonnes were flung upwards and ripped themselves to shreds. It grew and ballooned from dark ashen black into a veined fireball sun that scorched the campus square and blistered its onlookers with violet-green vision. It magnified and crested, and there was for a brief moment a feeling that it couldn't happen, that nothing made sense before the onlookers realized they were on the floor.

The engineering building heaved then and groaned in metallic death with a final heart-wrenching steel note. Its western side was gone and snippets of dead structure lay scattered through the dense smoke. Where its parts had gone no-one could know, and scattered viscera that had once been walls and labs and lecture rooms lay there for someone to ask – did I once sit here? And the building's last semblance of structure on the western edge slid then into the crater where there weren't any turbines, not any more, to catch fire and leave anyone who'd not been lacerated to think forever afterwards – who could've hated us so much?

***

They sheltered in a basement stairwell outdoors and barred shut the door behind them with old pieces of forgotten scaffolding. They'd shown Raynes and Schofield the maintenance report and the section on reverting it all. The agents said nothing of the betrayal, merely read the passage and nodded. Amy curled her knees up to her chest next to April. She screwed her eyes shut with the blast that resonated through the Blackett concrete and which tried to shear through the hinges of the maintenance door they'd come through. The shockwave passed. The stairwell was a shaded place. There were air conditioning units mounted high above in the brickwork and it felt like the sort of wet, cigarette-ridden place that no-one knew what to do with but which inevitably had to exist to connect the tunnels to the garbage disposal bins peeking from behind the ground-level railings above. Raynes was up first, and she followed him to clatter her way up the staircase where the smoke plumes had rolled through to blot out the sky in eye-watering graininess. Raynes held on to the rails and spluttered as he went from recently poisoned by gas to poisoned now by approaching smoke. The burning haze roared through and from her place behind the bins she leaned out to see the rising deep plume above the buildings on the other side of campus. On the wind she heard screams, high and low, car alarms of all kinds, and beneath all of it the deep yells of armoured CTC. Stay calm. There was panic on the upper walkways and campus shops, too far through the smoke to see. "Madam, is there anyone in the building injured?" someone in the distance screamed.

"Get out of sight, behind me," said Raynes. She was pulled back into the shade behind the huge bins. Raynes stifled his coughs.

"Move this way. Leave your belongings behind", roared someone in the background. Boots clattered down the access road and towards the explosion in unison.

"Are those the counter-terror police?" she asked.

"Stay quiet." Raynes took out the Starlite pistol, chambered it with one of his final magazines.

The sounds of running feet came the other way now and the commanding voice got louder. "THIS WAY. GET BEHIND THE POLICE BARRICADE. SOMEONE WILL BE THERE TO GUIDE YOU." And then the crowds came. Dozens of them clattering through the thickening smoke, those furthest from the blast first, half-jogging as they were shepherded by the police through the access road and around the edge of the Blackett building to the police perimeter surrounding the university. It wasn't just police now. The army vans had arrived in force.

"Paul -", hissed Schofield hidden a few steps beneath them on the stairs.

Raynes squinted through the thickening smoke and gave hand-signals to stay quiet. Schofield half-stepped, half-staggered his way up with his bad foot and bad knee while the rest struggled with April to bring up the rear. The huge man grunted hard and wheezed through the thickening plumes to crouch behind the bin next door.

"Amy, this time for once you're going to tell me the truth." She glared at him, eyes-watering and only able to make out the creased bald forehead in any real detail. "You're going to tell us how long we've got until Matt's next word, and then we're going to end this. Report or no report we need to know." She'd told them what she'd found, told them what the report said. April had just smiled when they'd shown it to her, and hadn't been able to say much more.

"The heat's bearable."

Schofield struggled, his bad knee taking the brunt of his weight crouched. "Bearable? What's that mean? Five minutes? Ten? Twenty?" He spluttered.

"Ten. At least, ten minutes before we can get the first thing we need for this to work," she whispered back. "I don't know. It changes in how fast it sort of build-up". Matt was behind the huge man, hidden by the stairs, also staring her down. "We need the first two at least."

Schofield nodded wearily, and stared off into the middle-distance. He'd heard it all as they sat there waiting for the explosion. "What's done is done. It's too late for the keys and too late for second-guessing. Just be thankful this gives us an alternative," he wheezed. "I hope you can see, finally, we're on your side."

"I didn't know about the black door. I didn't know it would do that." she said.

Schofield said nothing to that. "This is on your shoulders now. For better or for worse we're going with this plan. If it works, we're even. If it doesn't work, we all die. That way we'll be even too." He looked past her and whispered. "Raynes is it smoky enough for you yet?"

"Soon," replied the American. "Stay close, act calm." He turned to Matt. "You're positive about where we need to go?"

He nodded. "Sherfield, the biology building, fourth floor."

"You're sure?"

"I'm sure. Lecturers print handouts there before class," said Matt.

Schofield assessed the group and turned to Lana.

"Don't look at me," she said. "It's a biology building not a physics building I've been there only for the symphony recitals".

Schofield motioned with the revolver to Matt, tucked it into his jacket. "Fine. Lead on."

Matt emerged first from the hiding place with Raynes. The road was almost unrecognizable. The other side melted into blurred black shapes where the crowd moved, herded by steadfast police markers. "KEEP YOUR ARMS ON THE PERSON IN FRONT. MOVE FORWARD. PLEASE STAY CALM." There were blue-dot flashes of sirens through the smoke, crude shapes with bulky armour, screams and people coughing. You did this, the thought came to Matt but he pushed it away the same way he'd pushed away that same thought all the other times when it had come up, and buried it deep in the folder marked 'for later'. Just save it for later. There'll be time to think about ethics. Right now keep walking, follow the brickwork of Blackett. Stay as far away as possible from that crowd. You're got to go the opposite way to the masses, stay hidden. The further you walk, the thicker the smoke, the safer you'll be. But he couldn't convince himself as the smoke burned and he struggled to breathe through the fabric of his shirt that was wine-soaked with the last of Schofield's bottle. He just hoped April would be okay. Of all of them she suffered the most to just get up and move. He turned to check and saw he could only see Raynes with his makeshift bandanna and Amy fading into milk-dead whiteness. He felt his way forward to the next building. KEEP MOVING, STAY CALM. The sounds of the CTC officers got dimmer. He repeated the lines to himself. Keep moving and stay calm.

"Oi! Sir! Over here! You there-" someone shouted behind and was cut off by the teeth-shattering pressure-waves of gunshots. The lightning-flashes cut through the milky-whiteness and Matt dropped instinctively to the ground. Three shots. He scrambled backwards on hands and knees and saw it was Raynes who fired.

"Get up!" screamed the American above the high-pitched ringing. Matt scrambled and a rough grip dragged him to his feet. "Go!" Raynes pushed him forward with his free hand. Matt saw it then, the back-entrance to the Sherfield biology building, through the mist, the home of lectures for him every day from nine 'till twelve. The windows were blasted out but they were here. He struggled to the door and forced it open and found that the door flung itself free of its hinges. The empty frame of the glass door clattered to the ground.

There was no-one behind him.

"Amy! Scott!" he screamed what felt like soundlessly into the empty whiteness. Four flashes, then another few followed closer to blast his ears but by now he could barely hear them. Then they emerged through the whiteness, Schofield first limping with his revolver open, Amy, and April, Lana with Scott near the back.

"Go. Don't stand there. Matt, move." The words came through racked coughs, sounded miles away. Raynes came last, groaning and shoving past with a CTC machine gun over one shoulder

The lobby of the Sherfield building was deserted and almost as white with smoke as the rest. Marble floors stretched out milky green and barren in all directions from the lifts at one end to the heavy-set '70s staircase and snack machines opposite. Stacks of free student newspapers and career leaflets from an upturned meet-and-greet stand flowed across the middle of it all and was stamped with dirt and blood from lacerations into pulped pieces. Smoke billowed against the few remaining Plexiglas panels uselessly. Raynes checked the machine-gun, and pulled out the magazine with some effort. It was a standard honest-to-god British issued MP5K. Raynes thought back to border security this morning.

"How many rounds you got left?" asked Schofield.

"MP5K is thirty max, right?"

Schofield nodded.

"So twenty four."

They followed Matt up the staircase to the first floor. Here the lobby was mirrored. On one side there was an exit to the campus boardwalk, where you could quickly go between buildings or find a bite for lunch.

"I have a pencil to write the list for the plan to work. We need the eraser from the gift shop," said Amy.

"I'll go," said Raynes. "You head on upstairs. The lights are still on and the building still has power. It might not soon." He turned to Matt. "Fourth floor?" he asked.

"Fourth floor lecture theatre."

"Raynes, you have a pair of keys?" asked Schofield. "Be careful on your way in. I'll set more as traps."

Raynes had all his - control key, shift, escape and all. Schofield pulled out more that he'd stolen from the second explosion. "I've got twelve," said Schofield, counting them. "Six copies of 'shift', and four copies of 'home', two 'escapes'. All identical."

Raynes turned then and left wordlessly out onto the campus boardwalk with its first-floor cantines, student common rooms and bank. There was a gift shop there somewhere. He disappeared into the smoke.

Matt went to help up April.

"Wait," she said, "stop, please. Give me a second, it's getting worse." She sat on the last step splayed on the cool Sherfield marble. "Just – let me catch my breath."

Schofield snapped his fingers at Scott. "Elevators. Go, check them." Scott pressed the buttons. It wasn't going to happen. The fire-alarms had been hit all over campus by now.

"Nothing?" asked Schofield.

Scott shook his head.

"Worth a try." Schofield wiped his forehead and covered his face back up with the handkerchief. April wheezed and the huge man winced as he crouched down to her level. "This is the last push," he said. "The last hurrah. After this, when we get to the fourth floor you can lie down, you can pass out, you can throw up. But here and now we need to go. There's CTC, and Raynes and I have shot two of them. That means knowing CTC they're probably getting back up again by now, April. They won't be far behind even in smoke. They all have body cameras, radios to communicate, and they'll be coming from all sides now."

"Schofield, it hurts, and I can barely see you."

"You're not missing much." He grabbed her hand and pulled. "I know you and Packard feel bad half the time, and even worse the other half. It's four floors, then you can rest." Schofield braced his back to get her upright the rest of the way and helped her walk. "Amy, how's it looking?"

She looked up from the mangled safety report, folded and unfolded a half-dozen times and ripped in three from where she'd given Matt the first front pages, and Lana the difficult parts to make reading it faster. Just like the thesaurus. Division of labour.

"I need the Dvorak original version of the music if this is going to work– that bit's been made very, very clear by this Venner guy."

"Let's go. Scott," he called over the smoky shape who'd tried and failed to wedge the elevator doors open. The first floor was starting to fill almost as quickly with smoke as outside. Rough-gravel glass lay everywhere. "Help with April. We'll need to arm the doors behind us and take the stairs"

"Arm them with keys?"

"If anything it'll scare the CTC shitless."

The main lobby of Sherfield with its wide-marbled atrium only extended from ground floor to first. Beyond that they'd have to take cramped stairwells all the way up. It was slow-going to second with April, and Schofield kept looking behind them.

So this was really it, thought Amy. If step one of the final plan needed a regular pencil eraser, step two was even more important. It was going to be the final Dali's phase, she supposed, no matter how it went. She'd hurried through the vital parts of the safety report and pieced together the basic outline of what to do. There was some comfort, at least. She read how there are many worlds. In one, Ichor was made. Another far-off universe she guessed was Otter's lands. And the one they were in now was dying just as the one she'd come from had died and become merely endless blackness. The plan would erase the heat and the cold for good, and hopefully kill the instability before Matt could harness it. That was the theory, made by someone infinitely far away...someone who'd studied this day, as history. She counted the steps up to third, and beyond that to fourth. April was practically limp, and Scott dragged her the final few steps before she collapsed against a wall and sat there broken on the bottom seats of the lecture theatre.

"Matt, you know this place," said Schofield, holding two keys, "put these at any other stairwells, or common routes to the theatre." He turned to the other "Scott, you take these other two and go down to the floor below. Put them in random doors you find. If you see anyone, run. Don't go any lower than the second floor. And be back in half a minute."

They went in different directions. "Whatever you do, don't turn the keys! Just leave them in there," he called.

***

Vision had gone monochrome, and no amount of wet rags soaked in white wine helped with breathing. The bandanna kept coming loose. Raynes narrowed his gaze to thin slits of tears and had to hold his eyes shut when it became too much. From what he'd seen before the explosion the campus boardwalk wasn't too long, but it was close to the blast with the gift shop at least half-way down the boardwalk right by engineering. Last time, in Dubai, the gas had filled up slower, he'd left it a shorter time and hadn't had to stay past his welcome. Maybe without the shootout, or if they'd been faster at the accelerator site. Too late now. This was far beyond what was expected. The light-headedness from the smoke was extreme. His hand ran across the bulletin-boards and lockers, crunched through blasted shards of windows that had once been the glass sidings of a common room. All of the destroyed scene was reduced to a few demonic metres of visibility and you could be sure there was no chance of reading anything out here. Couple of feet, maybe ten, maybe more. There was a first-aid box in one of the walls and he tore it free off its mountings and looped it onto his belt. He kept one hand whenever he could on the sling of his submachine gun and grunted when something that seemed like a blasted shop entrance came into view. Raynes struggled to open his eyes for more than moments at a time and took snapshots of his surroundings as he maneuvered through disintegrated plate-glass and into the carpeted interior. He paused to get some cotton out of the first aid kit and plug his ears. He was sick of not being able to hear after gunfire.

Before him there were shelves half-bare in chaos and when he stepped through the shattered glass of the storefront he found himself sliding on thick reams of paper that fell apart in what seemed like a slow-motion deck of cards. Pens and stationery were scattered somewhere in his periphery. It was all here, all on the floor, and none of it where it should be. He checked behind corners and found the one-room store empty as he moved from the files and folders to gel pens that crunched and spewed black on featureless carpet. He collected a few erasers more by feel than by looking. He'd take a glimpse, snapshot and process where it was in the smoke, move his hand, repeat. There was a lot of plastic, paper, ink on everything but he trawled through. He found a few different kinds of eraser and he took as many as would fit into his pockets. There was no point leaving it up to chance – might as well take them all. At one point he tripped on gel pens and sliced himself on glass but bit through the pain. Plastic shards were everywhere, and he struggled with the first aid box to bandage up the wound. It had been quiet after the shooting – only ear-ringing, and everything had deadened down to heartbeat. He heard something that broke the rhythm and there was a metal gong from where someone had hit something, probably the rows of lockers outside the store. Paul Raynes took a makeshift earplug he'd made from cotton in the first aid box out of his ear and listened for the sound of crunching glass over the ringing in his ears.

It was there, low, slow, deliberate. He blinked away the tears as best as he could and crouched down beneath the nearest shelf as a laser flickered somewhere off to one side. CTC. It could only be CTC. He struggled to hold still and angled the submachine gun roughly to where the laser had come from. The trigger was slick from where he'd cut his palm and he re-adjusted as best as he could. He came around the shelf with slow movements and moved to where in his mind's eye he remembered the door had been. There was glass there on his left somewhere-and he would have to take a huge step to avoid the shattered window panes. More single snap-shots of vision – take a step, stop. Again. Another half-foot to a place where there were no pens or paper. And another bigger one through the threshold. The lasers were there, multiplying, fanning and flickering out misty-green at chest height. Stay low. Don't let the light hit something solid where it shouldn't be. Stay near the walls, out of the centre of the walkway. Move slowly. He was out of the shop now. Opposite and not far were sofas and seats of the common room emerging from the gloom across the corridor. It was just a short way back to Sherfield where there was less smoke, and a chance at whatever this new plan was. Between here and there was the sofas to pass by, a few shops, no more, no less. But there was also the glass, and metal, and a hundred things that would trip him up. And, as he looked out into the corridor and the nearby shops he saw there were more approaching lasers. Raynes edged his way backwards, stayed low, as low as he dared, and turned his own laser on whilst the others swept in other directions, then slowly pointed it from ground upwards, same height as all the rest. They could see it now pointed the same way, and Raynes kept the same sweeping motion checking the corners. The only difference was that as they moved forward he stepped back, checked another corner or nook behind them by the common room sofas, fell a little further behind. Stay far enough for the smoke to hide your shape. Don't get too close. Just the laser and nothing else. He blinked as fast as he could now, trying to see as much as possible through eyes streaming. Some of them came out of the common room and onto the boardwalk, fanning out further and leaving him behind. And he edged further backwards until he was pretending that he was guarding the rear, and then dropped his aim down to stare at the floor as if he was checking behind something. Raynes shut the laser off and dipped into a small snack shop. There was a counter next to him with its explosion-blasted muffins and chocolate. He crouched behind it and counted to ten, then to twenty and leaned out a little. The CTC were ahead, not far, but maybe far enough. He edged his way back out to the walkway and past the last of the tiny university shops. He climbed through the destroyed doors of the Sherfield building – there were shouts below. He dropped a key into the destroyed building's doors in his wake. Maybe someone would be stupid enough to turn them.

***

Controversies remain – doubly so when it comes to the much-disputed evidence of a reversion mechanism for an unstable system. First described by Venner as a thought experiment in 2136 it was later discovered, with mounting horror, that copies of the paper outlining these ideas had begun to circulate in the infected worlds. Notably, this is despite Venner's text originating over a century after the Atomic Vice event. The major uproar, of course, came from the implied contact between our world and the infected, which was condemned both as dangerous and unethical, but ultimately unavoidable. Since then examples of strong contact between infected universes and other lands have come worryingly often, for instance..." – an extract from 'Time-dependent changes to AV observations (Silva et al, 2158).'

"She's getting worse," said Peregrine. "Schofield, she needs a doctor, medical attention, something." The physicist sat with April who was splayed over chairs in the front row of an auditorium

"This happened the same way before. She falls practically unconscious."

"And you let it?"

"Lana, you can't do anything."

"I know first aid."

"So do I, but it won't help." he replied.

"What's her name again?"

"April."

The girl moaned in agony.

"Both of them are affected," said Schofield. "Her and Amy."

Matt kicked over a cello and tried his best to strengthen the barricade to the Read lecture hall on the fourth floor of the Sherfield building by threading an instrument neck through the door handles. In honesty the room was a double-stair-fed mountain of desks. Amy sat near the back flicking through parts of the safety report, re-reading, noting. It was here in the lecture hall where the culture and life of a university gestated amongst the dim-lit back seats with full-throttle laughter. You could tell there'd been good times; the chairs wouldn't fold all the way up and most of the veneer was gone from the desks. She looked down the incline and reckoned this was what it felt like at the top of a ski-jump. On a normal day from here you'd be ready to pounce predatory at whatever lecturer was unlucky enough to be on stage. There were no lectures this afternoon. It was Monday evening, the theatre had been booked by the symphony orchestra society, and the people had been and gone. Cellos, double-basses, woodwind, coats, satchels, and cases were strewn uncared for, their velvet exposed. Schofield was happy. They gave him cover to hide behind.

"Aims! I got it. Sent to print," said Scott from the PC down by the stage.

"It needs to be the right one. New World Symphony. For piano only." She'd never tried Dvorak in her years of practice. This was supposedly a classical piece from back when America was the called New World. She stood. If the New World symphony doesn't print or if there's a paper-jam, we're dead.

"It's from four different sources so there's multiple copies sent to print, called Scott from down by the lectern.

"Stay quiet," hissed Schofield

"That's not many, we could do with more," said Amy as he bounded up the stairs Please. Please let the power stay on. Just for a few minutes until the printer finishes.

"Only one of them had the full transcript, the rest are extracts."

"That's fine," she replied. Maybe five minutes until Matt is ready for the symphony step of the plan. Just five more minutes and it'll be over. One way or another, with Raynes or without, it'll be over. Scott hopped past her and up through the rear doors of the theatre that went up to the fifth floor. The lecture theatre was that big. The bottom was on fourth. The rear on fifth.

"Miss Suzuyama, you've got to lie still. Just relax," Schofield whispered.

Her friend didn't have long left at this rate, Amy reckoned. She dropped the maintenance report and followed Scott. What if the printer's out of ink? Or paper? What if we can't smash the lock open on the piano? The thoughts coalesced in her stomach, rose up to her throat. She fell through the swing doors half-hot, half-freezing, aching and oxygen deprived and peaked around into the fifth floor corridor. Please let the printer work. I don't know if I'll play the symphony right, but if I don't have the paper, then-. Scott was by the machine. It was linked to the pc downstairs and looked like serious business. It stood there, scanning and churning out page after page one-sided. Bad for the environment, part of her thought. This isn't the time. Lecturers printed out a hundred hand-outs here for classes. Thankfully it was high-speed. How much of it am I going to have to play? Will I be able to? Amy looked as far as she could, as far as the stairwell at the end watched the corridor for movement. When the printer finished Scott dashed out of cover between some lockers grabbed it.

The pages were still warm and barely organized. They retreated from the slowly-penetrating smoke and back into the clearer air of the lecture theatre. Oh, this is difficult. Notes were splattered everywhere.

"Is it okay?" asked Scott. He flinched as a metallic scrape resonated from the burning building across the courtyard. There was no-one here yet. He'd borrowed Schofield's fire keys to lock the fourth floor and third, booby-trapped some other main routes up here on fifth. They didn't dare go lower down in the building than third. It should be clear. We'd hear them coming up the stairs. But he wasn't sure.

"It's fine," she said. "This is tough but Miss Kirkland was ruthless. Compared to other things I've endured, not impossible."

"Your teacher?"

"Yep." She flicked through the pages. "Eight years of piano-torture, Scott."

"I thought you liked to play?"

"I do." Amy had a moment of panic and when she realized she couldn't recognize the key signature and had to work it out with mnemonics and counting. She'd bitten her lip and noticed only as an afterthought. She dropped the papers beside the safety report and then went downstairs with Scott to help Matt stack chairs for a barricade on fourth. It was getting hotter, and colder, and the lag time between feeling lava-lamp hot and then mirror cold was longer, too.

***

Catching his breath in the stairwell Raynes leaned out - don't lean too far- to check the first floor foyer. From here in the stairwell he should be safe. The smoke-filled Sherfield foyer hadn't stayed empty for long. More CTC had arrived, and he guessed they'd be advancing across campus right now. The black-clad riot gear wasn't above him, not as far as he could tell, but still he waited in quiet to see what the CTC would do. They must've been downstairs on the ground floor before. Probably evacuating the rest of the civilians. And amongst the CTC he glimpsed through milky smoke on the far side were the unmistakeable odd ones out. They were cut and lacerated with glass but otherwise intact, weapons out. Navari's business jacket was covered with bulky Kevlar. Hortez too, except Hortez also had Schofield's guitar case slung on his back. Maybe he was planning to go up on the roof? No, they'd probably rushed straight here. There'd been no time to leave it behind. The smoke was too thick to hit anything with a rifle now. Thank Christ for that. He leaned back into cover. The stairwell was old, painted sickly yellow and wide enough that had an angle on the shoes of anyone a few floors above him. In one corner, beneath the stairs and smoking ominously through the cracks lay a trap door to what he assumed was the subterranean hellhole that burned and would keep burning until someone shut the gas off. There was no chance of escaping through there, or out of campus. He retreated up the stairs to second, then took it slowly to third. There was a key dangling from the door there – red-tagged, and the door was locked. The CTC either hadn't been here, or ignored the third floor. No -there were no boot-marks, no trampled and tracked dirt.

Raynes looked up through the centre of the spiral staircase and considered his options. He'd have an angle from up there, on fifth floor down to here. So that meant realistically he had two options. Either join Schofield now and stay there by going through the agreed route on fifth floor, providing a defensive line together from within the lecture room, or force the CTC to go through third and fourth if possible, making them go up to fifth through the opposite staircase. That would slow them down. Raynes made a choice, and decided on doing a mix of both. He went up to fifth and found a good spot at the top where he'd have an angle on third, made sure there were signs that would point him towards the lecture theatre. It was just down the corridor. Perfect. Raynes passed the printer and opened the double-swing doors.

"It's me," he said. "Don't shoot." Raynes stepped into the Read lecture theatre.

The theatre was a mess. There must've been an orchestra in here when the turbine room exploded. Instruments lay abandoned and all but the lightest were piled up against the doors at the side of the stage. Familiar faces peered from the rows of seats, keeping as low as possible. Schofield stood up from his position between two violin cases and lowered his pistol.

"Anyone out there?" he asked Raynes. Despite best efforts his voice echoed.

Raynes got closer, lowered his voice. "There's at least ten in the building, more outside."

"What floor?"

"Still in the foyer. I'm going to be on fifth. I have an angle on them there."

"Did you get an eraser?"

"I got a few." Raynes nodded and showed him. "How's your leg? Worse?"

"Fine," said Schofield wearily.

"I'll need your fire keys. It'll buy us a few seconds."

Schofield nodded and he reached into his pocket for a few spare. "If you've got any other keys you've not told me about Paul, then now's the time to use them."

"Only one shift, and I'm also out of mints," said Raynes. He took the first aid kit off his belt and left it by Schofield.

"Hand the erasers out." The fat man coughed and stifled it into his handkerchief. "Just in case you and I run into trouble."

Raynes did. One for him, one for Schofield. That left at least ten spare. Matt and Scott were with April on the bottom rows.

"Take these, keep them," said Raynes, handing each of them a few erasers. April was lying splayed across the bench on the bottom row, covered in a dust cover from the grand piano that made for a makeshift blanket.

"How is she?" he asked.

"She's breathing, but nothing else," said Matt. "I tried to shake her awake like last time."

"Don't. We don't need her awake right now. Do what you're doing, and keep her in the recovery position on her side. Do you know exactly what you need to write down step by step when the time comes?"

"I've memorised it."

"Make sure," said Raynes, and left them.

Further up he gave one to Peregrine who had her head in a ripped report and then rounded to Amy sitting at the grand piano. He kicked shards of destroyed instruments off the main stage.

"Here," he said. "Take an eraser." He put it on the keyboard.

"Thanks Raynes," she replied, her eyes on the music, fingers above the keyboard. Silent, but practicing. And shaking.

And the piano itself was enormous. It was a full-sized Steinway. Raynes saw the black marks on the stage from years of moving it, saw that it must've creaked on its steam-roller-like wheels from its normal place in the corner to sit here at this end of the room farthest from the doors and the barricade. It had been stripped of its protective cover, the top opened and the sheet music spread out in a full set across the entirety of its length.

"That the New World symphony?" he asked.

"It is."

"Those pages are going to fly off when the CTC arrive and start throwing grenades. They can see you all the way from up there."

"I need to practice."

"If you hear shots, you take cover, and you don't start playing until you're sure that we're ready to go. I'll be on fifth floor." The lid protecting the piano's keyboard was damaged, he saw, its veneer freshly crushed in, the lock destroyed. He looked from the piano to its player, and thought best to keep his doubts about this his own.

"Be back in five minutes," she told him. "We'll be ready."

***

It was time to find Schofield. Bianca Navari lost her patience a damn while ago. She gripped her pistol and followed the CTC up the stairs last in the column, relegated with just Hortez behind her. Move faster, she wanted to say to the CTC, for Christ's sake. She felt like shouting at them, telling them that it's only two people. The longer this takes the worse it'll be for us. The sooner the better. She felt trapped amongst the few in the stairwell here behind boots that were checking every corner, doing hand signals, callouts. There could be more bombs for all she knew. Move. The CTC were combing the buildings slowly. The longer we wait the more they'll destroy. She knew Raynes, knew bits and pieces of what he could do. Raynes might be only transferring data from country to country but it was quite a responsibility to be doing alone. One CTC stayed to guard the bottom, others fanned out through other stairwells. Some filtered out at second. One of the battering rams went with them and blasted its way through anything in their way. The whole thing was well co-ordinated if anything. The other biology buildings opposite, the remainders of engineering, aeronautics, the lot of it was going to be searched. Manpower had arrived.

She passed the door to second and looked back at Hortez. He still had the rifle, and it was a burden he hoped he'd get another chance to use. He looked at her grim. Navari had given Schofield the benefit of the doubt three times by now, at least, if not more. She'd overruled Hortez, hadn't she? So this was on her, it seemed. Not all of the blame was hers, but enough to hurt. The cuts from the explosion felt deserved, the skin-deep lacerations grazed her all across the face, chest, legs. The body armour burned the most.

"This time is my turn," she whispered with venom. "Ready or not, here I come."

They'd stopped again, this time just below the third floor. She was far away thinking of Schofield's letter. That bloody letter. Why would he expect that she'd listen to that, or try to help? A CTC officer turned the key. Wait, thought Navari, that doesn't make sense. Fire escapes shouldn't be locked-.

The man disappeared.

Then she stepped back as she was forced backwards as the people above instinctively stepped back to aim. There was a split-second of quiet shock. Then the CTC fired. Chunks of wood and steel were blasted through the fire door and the door was shattered moments later by a battering ram.

"Where is he?" she heard bafflement through her earpiece.

"Who was it?"

"Ludlow."

"Search the floor. Find him."

"What the fuck?"

"What was that?"

"I don't know, keep looking."

"We need more boots here."

They looked. Their CTC officer stayed missing. A 'home' key had done its job. "Fan out."

"What the hell..." whispered Navari. "The fuck was that?"

"It's like the ones we saw back at the Maths building. Same kind," he replied.

"Same keys?"

"Same tags," he replied. She was close enough that she picked it up. It had been flung free of the door, crushed underneath the weight of CTC boots.

"Nobody touch any keys. I repeat – nobody touch them. Break down the doors" she heard through the earpiece. "If anything is locked, break it." The transmission cut out. She'd fallen behind. Half the black-clad team had inched its way up near fourth. They were splitting up. It didn't matter if they split up, there were enough people here that there was no escape. Her mind was miles from it all – thinking back, replaying the key-turn. Is that what you wanted? These keys? But how? How is any of it possible? And above that, above the memories of good times betrayed and incomprehension, and Hyde Park was the worst thought: if they have those something so powerful then are they even still here? Did they use something like this?

She went up shell-shocked to the fourth-floor landing and made it halfway up to fifth before Raynes fired.

Something punched her, and she fell back winded, deafened, stunned, careening onto concrete. She saw it in split-second fading motion – the gunfire ripping and tearing at the fifth floor team, hitting glancing blows, felling some, missing others. Chunks of powderized plaster were in her eyes. It was over in moments, and then the CTC responded in force. They annihilated the upper stairwell. Navari tried to catch a breath. She struggled and forced herself to try and breathe as the air screamed and ripped itself in gunfire around her. She held on to the steel rods of the banister and found that her vision was tilting. No, she was moving backwards, someone dragged her. Her chest was numb. She looked down. It was dark on dark but her hand came away wet.

"Keep the pressure on, Bianca. Stay here"

Hortez stepped around her, and she saw his feet as he ascended the stairs to fifth. The door at the top was locked like the others, and a key dangled. Hortez had had enough. He'd had enough of not understanding, of being a step behind. He didn't hesitate because he knew he should've hit them at Hyde Park. He should've hit Schofield dead. But the bullets had curved with the ducks flying in the way, and he'd missed every damn shot. It wasn't his imagination. And there were the keys, and the rest of it, and now this madness. He shoved his way past and heard the group command scream 'cease fire' as he turned the key he found on fifth.

***

There were no more mints that could help with the nausea, Raynes checked and checked again. He'd prepared. He'd tried his best and locked the door behind him first with fire-keys, and then put a 'shift' in there for good measure and braced himself to turn it when he ran out of ammo. He thought he'd got the hang of shifts. The world swam and he let the empty machine gun swing on his shoulder freely. Move. Get up or crawl away. Ignore the nausea. Raynes tried to stand, propped himself up, looked behind him and changed his mind. I'd forgotten quite how bad it is but at least I'm not on the stairwell. He crawled away from the door to the fifth floor stairwell slowly, got out his pistol, rolled onto his back to face it. Shots rang through the wooden frame to bury themselves somewhere in the ceiling lamps. He stayed low, edged backwards, heard the shouts and screams from other side. Good. You hit some of them, they're hurt. For every one hurt, another has to take care of them. The CTC had been ready to fire back in an instant. There was no underestimating them. He'd shot to hit as many as he could but an MP5K is little use firing blindly. The pistol wouldn't be much use. The ceramic was slowly coming apart. Vaguely quieter than an MP5K maybe, but no better. The shots through the door stopped and he felt the vibrations as someone slammed a battering ram the other side of the door.

Then he appeared.

Raynes scrambled. He had the advantage even as the huge mass of muscle that was Manuel Hortez descended. Hortez fell, almost in slow motion stumbling and fighting against the nausea to take the last few steps and grab hold of him. Raynes kicked, kicked again when Hortez clamped his arms round his feet.

"Get off me, you ignorant asshole." Raynes struggled free, stumbled and managed to stand, his suit in tatters.

"Schofield! Goddamn you, help me out here!"

The fire door to the fifth floor was collapsing. Raynes glanced up. Twenty seconds, less, and he'd be face to face with CTC. He kicked Hortez down again and pulled at the huge stunned mass of muscle and began to drag him, freshly teleported through a fifth floor stairwell. Raynes got up, struggled with the gigantic man. It was hard going and he slipped. Abandon him. It's not worth the risk. But the lumbering mass of Patrick Schofield was ready, revolver pointed. One arm joined him to drag Hortez a few feet down the corridor, just far enough where they'd have some time, some space to breathe with the lockers as cover. From here Raynes could see the door to the Read lecture theatre. Safety.

The door splintered from the other side. Schofield aimed roughly at the fifth floor stairwell and fired then. It was a gun rarely used, as little as possible at the outdoor police training course in Surrey, and as little as possible during work. That was his motto, and his ethos when it came to carrying a section five firearm. But when he needed to fire it there were no half-measures. He hadn't broken his wrist yet. The door imploded with a hole the size of a baby's fist, flinging the man with the battering ram backwards.

"Get him inside," said Schofield. "Peregrine, help us out here. You got Hortez but where's Navari?"

"I didn't see her."

Schofield fired again, flinched. Raynes had shared the cotton earplugs with him but it wasn't enough. The Englishman flattened himself against the lockers. They'd be coming from both sides of the corridor. And from below on fourth. Maybe through walls too. He hobbled painfully as he repositioned himself further into cover and noticed almost bemused that Lana had the empty MP5 pointed at Hortez.

"Amy, how close are we?" roared Schofield

There was no reply.

"How close?"

"Let Matt concentrate. We're down here."

"Soon?"

"Soon."

"Then get on the piano," he called, and blind-fired another few shots down the corridor. When he faltered Raynes leaned out the doorway with Hortez' sidearm to cover while Schofield reloaded.

Matt tried to concentrate. He clenched the sheet music as hard as he could. This had to work. The man who wrote those articles, Venner, said it should. And as stupid as this was to never feel when and how the magic had happened he'd keep going, keep repeating the words over and over in his head until they lost all meaning, until the words 'New World Symphony' became only noise, meaningless. And that was when it would get its other meaning of taking them to a real new world, and lose its first meaning. The new world meant America, the colonial frontier, but now he'd change that. So Matt kept repeating it, and lay there oblivious on the carpet curled up as tight as he could beneath the rows of seats. The shivering was getting more intense – there was only his heartbeat, his body uncomfortable on dark carpet and the music. Take us further into the New World, please, and then take us back to the Old World when she plays the damn thing in reverse.

He lost his grip on the music and opened his eyes as it was ripped from him. Amy was up, single-purpose and halfway down the stairs. She stood by the enormous instrument, flung open the lid so hard it smashed against veneer and resonated. Which was page 1? She looked at page two, three was there. The symphony looked the same. She could barely see it, eyes watering, hands shaking. Why did everything feel so weak, why was she so light-headed? She knew the first section, stared at the music with the heat and the cold dissipating. No. Start in the middle. You'll need to leave enough room to play it in reverse. Amy went for a random chord in the middle. She played.

The outside world a few feet beyond the piano flexed. It dimmed, went dangerously see-through to leave only blackness. She stood, feet on the only patch of ground that seemed stable and listened to the chord resonate. It was blackness absolute further beyond the last rows of the lecture theatre. Schofield and Raynes were about as far as she could see. The back wall of the Read lecture theatre was gone. Everything was freeze frame. She looked to the next chord, played it. The blackness pulsed, and like stills from a film reel the surroundings snapped out of focus and slowly came back in. Raynes had stepped forward, Matt was now mid-stride towards her, almost at the piano. And up near the door she saw Patrick Schofield reloading in freeze-frame, grimace on his face, and Lana with a gun on Hortez, dragging him down the steps as best as she could towards the bottom rows, and April dead to the world. She let the note die, and the walls returned to the Read lecture theatre, and the New World that was so unstable already got a little more unsettled with this new law in play. The piano that could reverse the music.

"What the hell? You disappeared. Does it work like he said?" Matt was here.

She nodded. Yes. Finally. Finally we have a real plan. "It works." Scream Amy, she thought. Shout like you've never shouted before.

"Schofield! We're ready."

"Raynes, go," shouted Schofield. Raynes backed away as Schofield emptied his pistol in both directions. He didn't have time to shout 'flashbang' before he saw it roll through the theatre doors. That's when the fourth floor door below, its barricades of cellos, instruments and all, detonated and imploded in fragments. And at the same time the Read lecture theatre cracked into pure blinding light above.

"Run. Raynes, get to Hortez!" Schofield couldn't hear himself. He'd flinched and that had saved him. Hortez' gun had saved them too. Manuel Hortez himself was the only card left to play. CTC burst in through the bottom doors. Schofield half-fell, half-jumped down the stairs, winced in pain and trailed blood down to the stage.

"Nobody move or Hortez dies," screamed Raynes. "Cease fire. I'll shoot him right through the goddamn head." Raynes had taken over from Lana, edged backwards down the stairs as Hortez struggled barely-conscious in a chokehold. There were CTC everywhere and they'd filed into the back of the theatre, by the stage, down the stairs. Some were in the projector room. And right at the back for a moment he thought he saw the hunched and pained figure of Bianca Navari, arms bloodied and struggling to stand.

Raynes edged to the piano. "Lana, Scott. Get April, quick. For fuck's sake." They dragged the one barely-conscious beneath the piano as Raynes looked from one CTC group to the next, saw each group closed in and moved forward when he looked away.

"Drop the weapon, we have you surrounded. We won't hesitate. Raynes, give up."

"Shoot Raynes and Hortez gets a hot magnum round through the back of his head from me too" replied Schofield. He'd bluffed with an empty handgun many a time.

A few more steps back towards the piano. Raynes edged his way until he was leaning on it. They all clustered around it, then, behind Schofield and Raynes at the front and as far from the CTC as they could. Scott had dragged April, laid her as near it as possible.

"Paul, Patrick, let him go!" screamed Bianca Navari from the back of the theatre. She struggled down the steps and parted the wall of CTC officers. Hortez choked, struggled in vain.

"I'm sorry, Bianca," said Schofield. "I'm sorry we never gave you an explanation. I'm sorry we can't take you."

"Drop the gun, let him go. For God's sake Hortez is your friend! We went to Christmas dinner together. And you," she looked in venom at Raynes. "you shot me. You actually shot me."

"We're sorry Navari". Raynes edged back and felt the cool of the piano against his back. "We couldn't let people use the keys, or any of it. What you've seen is real. The world stopped making sense this morning, and we've been trying to put it back together."

"You blew up-" she struggled "-a university."

"Play, Amy," said Raynes.

Raynes dropped Hortez and the world beyond the piano disappeared into black and flexed. She played the New World symphony then, and played it forward. The darkness got stronger, the freeze frames further apart with each chord. Hortez being taken away by stretcher. The CTC crowd – one moment there – the next freeze-frame gone. And in the middle on the bottom row sat Bianca Navari for a few moments before her image too was gone with her utter sadness and streaks of mascara. The Read Lecture theatre fell away. She played more, and the snapshots of the notes blurred themselves faster and faster into bigger steps as they moved further and further through the New World's timeline. The snapshots turned to hours, days, longer. The heat and the cold fought irrationally in her, up and down with each snapshot. With each chord time passed, and the heat and cold rose and fell in the swell. The hours passed and then she found a snapshot of time where the heat and the cold were near their peak. She stopped playing.

"Now," she said. "It's time for the eraser." The blackness flexed out as she paused. The lecture theatre and its surroundings returned. The room was dark. Completely black. The power had failed, there were no back-ups any more, the back-ups had burned away. The CTC weren't here, or the detectives. There was a cordon where the piano should've been. Matt took a deep breath, sat himself on the lid of the piano and cleared his mind. He held an eraser. This is the end of it. His ears rang, and felt as if they'd never stop now. A few of them left the piano one last time to look around the dead deserted Read lecture theatre in the middle of the night. What day it was no-one could say. A day, a week, a month had passed? Amy peered through the hole left by the explosion where the fourth floor lecture theatre doors used to be and gazed out onto the corridor, and out beyond the corridor to the smashed full length windows and the campus square. The tops of the campus was dark, completely. There were still cordons everywhere when she looked down from the edge and temporary tents were scattered. To one side was the wreck of the engineering building, now dark and desolate. She winced as the heat and the cold peaked slightly out of phase with each other and slowly began to fall away. The destroyed instruments had been cleared. The only thing left was the piano battered from shrapnel and travelling through time with the symphony. April had been lifted onto the lid. Scott sat next to her with Matt. Schofield and Raynes just shared the stool.

"What now?" asked Matt.

"Now we check if the eraser works," said Lana. "Venner says it should delete anything that's written in pencil."

Amy took her stolen pencil from the Vire Tower art exhibition, still inscribed with runic from the land of dead sunsets. Someone took an unused sheet from one of the New World symphonies, she began to make a list. The words 'Patrick Schofield's revolver' were written in block capitals and the gun itself kicked to the other side of the room. Matt took the eraser. He used it. And when he looked up the gun was gone.

"Venner was right." said Matt. He didn't smile.

She looked to April, barely breathing, still near unconscious despite the gunfire and wearily stumbled back to her position standing over the piano. They were on page three. She played it in reverse this time. The New World symphony would be undone and with it the New World itself and its toxic horrors would go in reverse and die, and be buried as if they'd never happened. This time, Otter, I don't need the reverse key. The world beyond the piano seemed to flex, bulge and scream in sharp horror as the Read lecture theatre groaned its way backwards, the days reverted, the hours fell back. And then they passed the point where she'd started playing. Here the world outside blurred into groups of different meshed places. She played page two in reverse. There were ghostly tunnels overlaid with an office, massive generators stood silent. Then leafy greens blurred past, and a violet smear, and tiles of a hospital. And then Amy played her way through the first page of the New World Symphony, back to when they hadn't known as much. It was slow, but she'd practiced, and the keys of the piano strobed and changed in technicolour shades as the world around the piano moved through different places and as the New World Symphony ran its reel in reverse. There were the final few bars. And as they came she slowed down, and saw that nothing beyond the piano made sense. It was only chaos, a mess of overlaid perspectives from each of them, and beyond that, darkness. There were two things left to do that had been in the report. The first was Raynes' duty. There must be a clear separation between the victims of the anomaly and the effects of the physical laws itself, Venner had written. The greater and clearer the division, the greater the chance of success.

Raynes took a step as Amy played on. He picked up April's arm. He would have to wake her now. She needed to be as normal as possible so she'd not be erased too. That was the long and short of it. And she couldn't be practically comatose. He pointed Hortez' glock roughy and shot her. April screamed, torn awake and her arm crushed hanging at an angle. She fought as Scott pinned her down, and as she kicked and thrashed against the piano in agony. Blood spurted from the wound and bathed her slick, streamed and pattered onto her keyboard. Amy frowned. Just keep playing. This is it. We're almost there. She wiped her face, tried to ignore anything but the notes. Take it slow. Try not to make mistakes.

Third bar, second. The bar-line between the second and the first bar passed and with a passing thought Amy realized that the first two were not only musical bars but real bars in some of the timelines. There was the university bar where Matt and Scott had first tried to take their mind off of it, and in the background coming in and out of focus was a flight to London, a basement kitchen in halls, a control room to an accelerator.

"Now! This is it," she shouted.

The blackness pulsed. Matt stepped off the piano, saw himself and Scott in Hyde Park on the bridge as if through a distant mirage. He took two or three steps away from the piano and leaned on the balustrade of a real bridge in Hyde Park above a detector array for an accelerator. Beyond the edge of the Serpentine the horizon was blackness absolute. He did as Venner's escape plan written in the twenty-second century dictated he should go about this. "Remove the obvious changes first." So he did. Matt had the list that Amy had written for him. He erased the words 'Amy Packard's powers of the Atomic Vice', 'April Suzuyama's powers of the Atomic vice'. He continued. Next was the weird part. He took the eraser, put it on paper. The piano was still there- ringing in the notes in reverse as slowly as it could. The words 'unmerged mental states' were written in Amy's neat block letters. He erased it.

Matt blinked. The blackness disappeared. Scott was standing next to him. It was morning. He stood in his running gear, turned to see a piece of paper and a pencil on the balustrade of the bridge.

"Scott?" he asked. "Is it you?"

"End this."

Matt picked up the pencil. The piano was gone. They'd merged with their past selves. There were a few words still written on the paper. He forced his hand down as hard as it would go. As hard as he could to make the eraser remove this. Even though he was sure, almost certain that nothing except the last two on the list still existed this far in the past, he deleted them anyway. He had to make it so that none of this fucking evil ever happened. Stop it all.

THE KEYS OF THE ATOMIC VICE.

MAGAZINES OF THE ATOMIC VICE.

ICHOR SMARTPHONE OF THE ATOMIC VICE.

S552 ACCELERATOR 'ATOMIC VICE' POWER MAINTENANCE REPORT.

THE NEW WORLD SYMPHONY OF THE ATOMIC VICE.

Then he got to the final two. The final two which had to be done last.

MATTHEW HALE'S POWERS OF THE ATOMIC VICE.

THIS ERASER.