Marie Quinn is curled in the corner of UO Wyeleigh’s main freight elevator, descending, clutching a shiny black ray gun almost as long as she is tall. The gun has a two-tined prong instead of a barrel and its stock is a weirdly asymmetrical mass of delicate pipework, more like a Swiss watch or a small intestinal tract than a weapon. The gun is U-7381, and the severely disturbed physicist from whom it was confiscated went to her grave insisting that she didn’t build it, she summoned it.

A tornado of violence and destruction is tearing through Wyeleigh and through the minds of everybody working at Wyeleigh. Ceilings are being brought down. The site pharmacy is a sucking hole at the side of the building. The armory is buried. She had to settle for anomalous weaponry instead, retrieved during a brief stop in the underground experimentation labs. The Antimemetics Division operatives she meets in the corridors are all broken, some of them curled up and raving while their minds evaporate and they die one memory at a time, some infected with a collection of ideas that compel them to shout guttural phrases in strange languages, and to procure blades—never guns—and work on those demented victims, and each other, and themselves.

Quinn doesn’t recognize any of the people. Their faces are all wrong, torn up with misery and hatred and vindictive glee. She’s been trying to avoid fighting, but she’s had to kill one man in self-defense. Fired at his heart, U-7381 simply erased a half-meter-wide cylinder of matter, removing his upper torso and lower jaw. He fell to the ground in four pieces. U-7381’s beam is invisible, silent, and recoilless. It was like using a child’s toy gun.

Quinn is petrified, but more than that, angry. “This is too much,” she says, out loud, willing her heart rate back under control. “I can’t deal with this. I shouldn’t have to deal with this. It’s my fucking first day!”

■

But how much sense does that make? Quinn studies her reflection in the dark glass of the elevator control panel, and she tours the interior of her own skull, examining her thought processes. There are hints there, which would be difficult to articulate to someone who didn’t know her as well as she knows herself. She isn’t thinking like a newbie. She’s instinctively breaking the problem apart, the way an experienced Organization operative should. Hell, a newbie wouldn’t even know how to carry out a detailed psychological self-examination of this kind. A newbie wouldn’t even think of it; a newbie would just suffocate.

“The first thing it did when it saw me,” she explains to her reflection, “was eat everything I knew about the Division. And everything I knew about it. If I had a plan, it ate the plan…But I’m still me. So I can come up with that plan again. It’s already right in front of me, I just need to see it. If I were me, what would my plan have been?”

She scratches absently at her left wrist.

“Taking some hardcore mnestic drugs would have been a smart first step, I guess,” she mutters. “Reinforcing my mind, so that it can’t erase the rest of the steps. Damn.” The nearest source of mnestic medicine is the site pharmacy, but it’s already been destroyed, and in any case the elevator is headed down, away from it.

No. Stop. The pharmacy’s been destroyed? How do I know that?

Well, because she was there. She remembers finding the pharmacist crushed to death beneath a fallen medical cabinet, her skull an unrecognizable splatter of scarlet. She remembers the floor being torn away beneath her feet, and only barely making it out of that portion of the building alive.

She remembers—a modular red package with an enormous white Y on it, and a biohazard symbol. Her heart nearly stops at this. Oh, God. What did I do?

She remembers the dozens of warnings covering the package; she remembers the three-factor authorization procedure she had to follow to get into the sealed container where it was stored; she remembers the centimeter-thick book of medical advisory information, which she discarded; and, rolling her left sleeve back, she finds a fresh needle mark with a speck of blood, and remembers administering the injection.

This was my plan? This is what it takes to fight U-3125? I’ve killed myself—

Class Y mnestics represent the state of the art of non-anomalous biochemical memory fortification. Class Y mnestics permanently destroy the subject’s ability to forget. The result is perfect eidetic memory and perfect immunity to arbitrarily strong antimemetic interference.

The dose is taking effect now. Quinn didn’t read the book because she already knew every word of it. She knows everything that’s about to happen to her. She can already feel her mind hardening, like steel, and the developing symptoms of extreme sensory overload.

She can see everything.

There are extra buttons on the elevator control panel, the lowest of which, the thirtieth floor below ground level, she’s somehow already pushed. The walls of the elevator are covered with graffiti scrawled by the desperate and dying, people whose conceptual presence was eradicated from reality years earlier by the Adrian Gage antimemetic kill agent, reducing them to the level of ghosts. In one corner of the freight elevator there is even a half corpse, unidentifiable, so many layers removed from reality that not even flies can smell it, its cells winking out of existence asymptotically over the course of years.

There is a fistful of tiny white worms exploring the floor of the elevator car, near where she’s sitting. Revolted, Quinn shuffles back from them, shaking one or two more of them out of her hair. The worms are among the most widespread and successful antimemetically cloaked organisms in the world. They are everywhere, in every biome, in every room.

She can hear a long, alarming drone noise, a continual roaring that has the texture of ambient noise and is continually getting louder. It’s as if it’s been there for her entire life, and it’s only now that she’s begun to hear it.

And the memories. Short-term, long-term. The taste of every pill, the dull roll of every mile she’s ever driven. The man she killed, it was Ives. That should have been impossible but his movements made no sense—

It’s too much data. Too much sound, too much light. Having her eyes open is like jamming them full of needles. She clamps her hands over her ears and screws her eyes up. Even like this, she feels the vibration of the elevator’s slow descent and the heat of the failed air-conditioning and the movement of her clothes on her skin, and meanwhile her vision is flooding instead with what could be hallucinations. The human sensorium routinely generates huge amounts of data, and the human brain is adapted to discard almost all of that data nearly immediately. Altering the brain’s behavior to retain that data is extremely dangerous even for very short time spans.

Quinn takes one hand away from her ear for just long enough to punch the metal wall of the elevator car, bloodying two knuckles. The pain gives her a focal point, a memory that screams a little louder than the rest.

And she finds the plan. The plan that was always the plan, the plan that she’s rebuilt a hundred times, synonymous with her whole existence.

“I can beat you,” she says. “I know how.”

“No,” U-3125 says to her. “You don’t.”

■

The elevator stops at the thirtieth floor belowground and its doors grind open. They wait, open, for a long time. Farther up the elevator shaft there are the distant rumbles of more parts of the Wyeleigh complex being reduced to rubble.

Still crouched in the corner, Quinn mutters, “U-3125 doesn’t have a voice.”

“Die wrong,” it suggests.

“U-3125 is a five-dimensional anomalous mass of corrosive ideas, seeping through to our physical reality. It isn’t coherent and it isn’t intelligent. It can’t communicate. This is an auditory hallucination.”

“That’s all you are, isn’t it, Marie? Dead wrong. Over and over. How many people are buried under that judgment of yours? And you’re still here. All those lost battles, every year of that entire lost war, but somehow you always find enough dumb luck to walk away. The eternal sole survivor. You don’t deserve that kind of luck. Nobody does. Do you know what you deserve?”

While it’s talking, Quinn leans hard on the ray gun to get to her feet. She lodges one shoulder against the wall of the elevator car, still with her eyes closed. She braces herself, and opens her eyes. The corridor ahead is empty. There’s an airlock at the far end, this one large enough to drive a truck through, built from ultra-toughened white metal alloy in Ed Hix’s established style. There’s a panel beside the airlock. She closes her eyes again and hobbles forward, using the ray gun as a crutch, stretching one hand out ahead of her as guidance.

“Someone has to be last,” she says, gritting her teeth. “Someone has to be the best.”

U-3125 follows her. “Do you remember how your mom died?”

“No.”

“What it was like to watch? How long it took?”

“No.” She’s lying. It was the worst thing she had ever seen. She tried so hard, for so long, to forget it.

She reaches the airlock.

“Your whole Division is dead. Minds scooped out, like eyeballs. Hollow people, holes in space for brains. It’s just you, Marie. Dying from mnestic overdose. Buried alive. Up against an immortal, unkillable idea. You’re going to find out. Not long now.”

She fumbles blindly with the panel until she finds the slot for her keycard. For a few seconds it seems as if nothing is happening; then a yellow light flashes, the enormous mechanical interlocks unlatch, and the door cycles open with all the fuss of a flower’s petals unfurling. Noise, Hix always held, is a symptom of imperfect engineering.

Behind her, she hears the freight elevator close up and return to ground level, and she knows that someone has summoned it, intending to pursue her.

“Ideas can be killed,” she says, stepping into the airlock.

“How?”

“With better ideas.”

As the airlock cycles closed, so does the hermetic seal. U-3125 falls silent, shut out.

■

If something can cross over from conceptual space into reality, taking physical form, then something can cross in the opposite direction. It must be possible to take a physical entity, mechanically extract the idea that it embodies, amplify that idea, and broadcast it up into conceptual space. A bigger idea. A better idea, one designed specifically to fight U-3125.

But what entity? Where do you start from?

The machine Quinn needs to build, the amplifier, is the size of an Olympic stadium. And she doesn’t have a fraction of the heavy memetic engineering experience to do it, let alone the material resources or the time. But she knows—she has always known—that an Antimemetics Division operative is as good on their first day as they’re ever likely to be. And the same must be true of the Division as a whole.

The Division has to be good enough. The idea of it, the fearless ideal. She, who embodies the Division, the last and fiercest, has to be good enough.

She tells herself: We won this war on the day it began. When we encountered U-3125 for the first time, we built this bunker. Ed Hix faked his death and sequestered himself here so he could work uninterrupted, while the rest of the Division held on for as long as humanly possible, buying time for this moment. I know this is what I did, because it’s what I would have done.

You start from a person. I’m the final component. He’s waiting for me.

■

The space beyond the airlock is gigantic, structured and lit like an aircraft hangar and filled with hot, stale, dry air. Quinn, still mostly blind, stumbles forward across an expanse of more than a hectare of flat, dusty epoxy flooring. “Hix!” she shouts into the void. “It’s time!” Nothing comes back but the echo.

She glances up for a second. The space is empty. The castle-sized memetic amplification/broadcasting unit that Ed Hix was meant to be building is absolutely absent. Hix himself is absent.

Maybe the entire machine is antimemetically cloaked? she wonders, momentarily. It would be a smart way to conceal the operation even from the rest of the Organization. But her brain is curdling in some of the strongest mnestic drugs imaginable. There’s genuinely nothing here.

Almost nothing. At the center of the space there’s a small outpost, a group of trestle tables with tools and toolboxes scattered about. Parked behind it is an unmarked military truck with flat tires. On the back of the truck is a squat, squarish machine the size of a shipping container, with unshielded wiring and exposed pipework, and a long cable leading to a heavy-duty control panel on the floor. To the untrained eye, it is not at all clear what the machine is designed to do.

It is the antimemetic equivalent of a hydrogen bomb. An ultimate emergency measure. Activated, it will blast a gigantic hole in ideatic space where the Antimemetics Division was. There will be no Division and no UO Wyeleigh afterward. Wyeleigh will be a forgotten zone, an unlocatable irrelevance, isolated from the rest of reality. Its staff, whether on or off the site, will drop dead on the spot, minds flattened, and disappear from the collective memory of the world. The Organization will continue onward, oblivious to the sucking wound in its org chart. Mahlo won’t blink as it happens.

It’s the wrong machine.

It can’t destroy or contain U-3125, or even injure it. It is aimed in the wrong direction, and it wouldn’t matter if it weren’t. All it can do is sterilize today’s outbreak. The other symptoms will persist. Fifty or ten or five years from now, or maybe one year or maybe tomorrow, U-3125 will return, bringing with it its Cat. ε scenario. Human civilization will be entirely eradicated as an abstract concept and replaced with something unimaginably worse.

Quinn leans there on the ray gun for a long moment. The pressure of information in her mind, continually increasing, reaches a point where she can’t take it anymore, and she starts to break. Five decades of memories are screaming at her. It’s impossible to discern one from another, any more than she could pick a single voice out from a furious crowd of hundreds of thousands. The Class Y has been in her system for long enough now that she knows for a fact she has irreversible brain damage. There is no antidote. She’ll be lucid for another hour, then spend the remaining two or three hours of her life vegetative.

That’s right, she thinks. It’s almost a relief. This is good. This is right.

I’ve survived too long. I forgot which universe this was. For a while there, I thought, maybe…this was the universe where we win sometimes.

The agony in her head is like an ice axe, now. She drops the ray gun with a clatter, sinks to her knees, lies down, and waits for either death or a better idea.

■

A being superficially resembling Simon Lee arrives at the outer airlock door. It examines the airlock uncomprehendingly for a few moments, then finds the keycard slot. It hunts methodically through Lee’s pockets, then remembers the keycard around its neck. The airlock cycles once more and not-Lee goes through. Behind it, the freight elevator is returning to ground level a third time, to fetch the others.

In the next room, the being that is not Simon Lee finds Quinn, unconscious, with the ray gun dropped beside her. There is also a military truck, which it disregards.

Not-Lee lets its keycard fall from its fingers and scoops up the ray gun. For a moment it contemplates the unconscious Quinn, then examines the gun itself, remembering how it works. It turns back to face the airlock and fires, punching fat cylindrical holes in the white metal of the inner door until it’s gone, then the outer door too, breaching the hermetic seal. A faint smile returns to not-Lee’s face as U-3125 and its familiar, comforting signals flood into the bunker.

Ten more non-people are arriving by freight elevator, former Antimemetics Division bodies. “I’ve found her,” not-Lee calls out to them. It drops the ray gun where it’s standing and pulls out its knife again. It holds the knife between two fingers, in a casual, offhand sort of way, as if it were a pencil or screwdriver.

The infected non-people gather with not-Lee around Quinn, looking down at her with expressions of disgust, or pity, or malice.

“Why isn’t she ███████ ██ properly?” someone asks. “She can’t meet them unless she’s open.”

“Start with her eyes,” says someone else. “It’ll make the rest of her easier to correct.”

Not-Lee leans down to start work.

Quinn’s mind is uninhabitable now. Her thoughts are like sludge, a concentrated, toxic slurry of everything bad that has ever happened to her. But there is something else there. A tiny, barely perceptible glint of unexplained, unsnuffed hope. A ray of sunshine.

Muck folds over it and swamps it, instantly. She doesn’t know what it was. She doesn’t have thought anymore. But it was there.

Not-Lee hesitates, its knife a few centimeters from Quinn’s eye. She is whispering something, so quietly that only it can hear her clearly.

“None of this happened, Simon,” she says. “You and I never existed. There is no Antimemetics Division.”

There’s a sharp click as the bomb finishes powering up. Nobody in the room can hear this but Quinn. Nobody in the room can perceive the bomb but Quinn. All they can see is an empty truck.

The world goes black.