Listen: to the droning hum of the battery units. The sound causes Ava's scalp to tingle. Listen, remember: the scintillating purr of the ventilation system. It gives her goosebumps over her entire body. The tinkle of a trillion nuclei rattling around inside the reactor – come on, listen! Really hear it now: it's the score of science gone mad. This is the laboratory Mom built.

Her name is Sara, remember?

The soundtrack is familiar and Ava suddenly begins to recall some basic facts. She is certain this is the lab Mom had constructed inside the bunker. The bunker! A luxurious fall-out shelter where they will endure the End, a fantastically expensive property which Mother owns because she's a scientist. An inventor. Famous and wealthy – and obsessed with her work.

Obsessed with the work of cloning a human being.

As proof of concept, Mother had first duplicated Socrates – an albino rat. The task had taken months in the lab but the experiment was finally a success: producing a second, identical Socrates. Same beady red eyes. Same twitchy, whiskered nose. It was decided the second Socrates would be called Spartacus. And with that, Mother was ready to proceed. She was ready to clone—

The questions are never so complicated. In reality, they all share a single answer.

The truth is: the things inside us are too small to see and too massive to imagine.

“What is this?” Ava whispers to Bach, never taking her eyes off the woman who is at once both her mother and a sinister stranger. “I trusted you.”

“You don't understand,” he insists, “Sara is the doctor we talked about – she's going to help.”

“I may need your assistance restraining the girl,” says the Doctor. Ava's mother. She stands beside an operating table, inspecting and arranging a tray of silver surgical instruments. Torture devices, in the wrong hands.

“You son of a bitch,” Ava whispers to Bach, “you damned liar. This is a trap.”

“I have never lied to you. Not even once.”

And she realizes maybe he doesn't know. Somehow he has brought her all the way here, rescued her from the caravan and the Canon City creeps and the Scums – and maybe he doesn't know that Doctor Sara is Ava's mother.

“Bring her here,” the Doctor demands, completely unconcerned with Ava's distress, “we must get her connected to the apparatus immediately.”

“That is my mother,” Ava finally says out loud.

“What?” Uma asks, “are you sure?”

“Ava, I'm sorry,” Bach is quiet and warm but also steely serious, “you're confused. This doesn't make sense now, but it will once the Doctor does her thing. I promise.”

“Bach? I said bring the girl here,” Sara demands, and he frowns and looks at Ava, but only hesitates for that moment before moving toward her.

“You can't have her.” Ellie steps between Bach and Ava. She screams, “you can't have her!”

And Sara, Ava's mom, she laughs and says, “bring her here and kill the others.”

Uri snatches his sister by the sleeve and pulls her back. But Ellie maintains her position, sliding so that she is physically shielding Ava, her head on a swivel, watching Bach and Sara both.

“She's right,” Ellie hisses, “you will have to kill me.”

“I will not harm you,” Bach assures her, and then, turning to Sara, he shouts, “you contracted me to find and deliver the girl. I never signed up to be your executioner.”

“So be it,” says Sara. She produces a small electronic device from the pocket of her lab-coat and performs a swift gesture upon its touchscreen surface. “You're fired.”

And Bach collapses to the floor like a puppet with its strings cut.

“Bach!” Ava shouts, dropping to her knees beside him. His eyes stick open, staring blankly at the ceiling, spittle foaming from the corners of his mouth. “What have you done to him?”

“I've deactivated my malfunctioning minion,” says Mom, “but don't worry – I have others.”

She returns her attention to the device with which she disabled Bach but before she can use it to commit more evil deeds Uri and Uma join hands and chant rapidly and:

Ava perceives the psionic power's data in the moment before it executes. The screen of the device in Sara's hand suddenly flashes brilliantly and she yelps and covers her eyes and in doing so she fumbles it to the floor. Blinded, she curses and drops to her knees to feel around for it.

“We should flee,” Uri urges, “through the door she came in by – there's no other way out!”

“What about Bach?” Ava asks.

“What about him?” Uri scoffs, “he brought you here to fulfill a contract. He's a mercenary.”

“He did save us from Human Resources,” Uma mutters. Over on the other side of the lab Sara has found her device.

“There's no time for debate – we must go!”

He drags his sister by the arm and Ellie follows after. Ava waits behind. She looks down at Bach. He's still staring at the ceiling. A shadow of urine creeps out from his crotch, staining his trousers. Did he really bring her here to sell her? Has he truly been driven by nothing more than profit?

“I will return,” she says to him, not sure if she might be lying, and hurries after the others, past her awful mother, through a door beyond which there is only darkness.

“I think we've already been this way,” Uri sighs.

“We're lost,” admits Uma.

“This place is a maze,” cries Ellie.

“Can't you do something?” Uri asks Ava, “aren't you supposed to have some sort of powers?”

But what can she really do? A roundhouse kick? Summon some twigs? She has a gun—but no bullets—and if that isn't just a perfect metaphor!

“I'm sorry,” she says, “I don't know how to help.”

The smooth corridors seem to go on endlessly, all alike. Any doorways which exist must be hidden seamlessly – like that through which Sara had entered the laboratory. Soft lights sense the party's proximity, activating as they approach and dimming when they pass, creating a bubble of visibility around them similar to that which might have been offered by a lantern or torch. And after an indeterminable amount of time staggering through these smooth, steel catacombs they have become hopelessly lost.

“If she shut the door behind us,” says Ellie, “how would we ever know? Even if we were standing right beside it, the entrance to the laboratory would probably be invisible to us.”

“We aren't just lost,” groans Uma, “we're trapped in here like rats in an experiment.”

In her mind's eye Ava can't help but see Socrates and Spartacus – Subjects Zero and One, respectively. Their identical twitching noses. Their identical yellowed teeth and white fur. Their identical blood-red eyes.

“Maybe that's it,” she says, “maybe this is an experiment.”

“You think that woman,” Ellie pauses, “I'm sorry—your mother—you think she's set this labyrinth up in order to test us?”

“Not us,” Ava says, looking around for anything unusual, “just me. She wants to know if Bach did the job right. If I'm really Ava.”

The others exchange confused looks.

“Of course you're Ava,” Uma says, “we've all seen you in action.”

“Like when you blew out that brigand's brains,” Uri recalls, “that wasn't just something any girl could pull off.”

“It wasn't something any boy could do, either.” Uma punches him in the shoulder.

“But she doesn't know that,” Ava says, “because she wasn't there. And she's a scientist. She doesn't trust the word of anyone – that's all hearsay. She wants her evidence empirical. She has to prove it for herself.”

“You really do know her, don't you?” Uma asks. “How she thinks. How she acts. She really is your mom. I'm so sorry.”

“So am I,” Ava says.

“Can you get us out of here?” Ellie's asks.

“I don't know. I'm not sure what I'm supposed to do.”

She thinks back on the bizarre events of the recent past, the proof of her powers. She summoned a bundle of sticks once. She became instantly familiar with how to handle a gun. She performed martial arts without any prior training. Did these situations have anything in common? Was there a trigger?

“The identification numbers,” she whispers, trailing off.

“What?” Uri wonders – but it's too late. Ava is on her hands and knees, scouring for clues. She crawls to where the smooth, silver floor meets the smooth, metal wall. She feels around the way a blind person reads.

“What is it?” Ellie asks. “What are you looking for?”

“I'm not sure,” Ava answers without looking up, “but I'll know it when I see it.”

“This is crazy,” Uri pouts.

“Brother,” Uma crosses her arms and says, “just keep it to yourself, for once.”

With her face inches from the wall, Ava feels her way up. Nothing but smooth metal. Her own, unfamiliar reflection. Her own eyes. And is there something else? She eases forward, closer still, and it's as if there's something written there in the reflection of her pupil. She squints and:

“What in the world?” she wonders. The information extrapolates inside her mind faster than it could possibly be read but what is it, exactly? A character sheet? She can't help but think of the Scums, how Bach said they played a video game and forgot how to be human. Tears begin to well in her eyes. Is she one of them? Is this how it happens?

And as she loses focus, there it is, printed right in front of her on the wall like a mirage:

And all-at-once she knows the catacombs precisely, as though a map is being written in her mind. She can visualize where doorways are placed and there are even a few labeled points-of-interest:

Here: the door which leads back to Sara's Lab.

There, only a short distance back the way they've just come, a door labeled: “AVA.”

And now she can see that they truly have been creeping along in a circle. She laughs. But the door marked “AVA” consumes her thoughts. And the “character data” dump designated her class as AVA, too. What could it mean?

Uma touches her on the shoulder. “Are you okay?”

“I am. I am.” She wipes the tears from her eyes. “And I know the way.”

“A way out?” Ellie asks, sounding hopeful for the first time in memory.

“Yes, but there's something else I have to check out first, before we can leave.”

“What?” Ellie can't believe her ears. “Are you crazy?”

“Ellie.” Uma tries to comfort her but the older woman pulls away.

“Come on,” Ava says, “follow me.”

She stands before the door and only in her mind's eye is it labeled 'AVA.' Here, in the real, material world, all anyone can see is the unmarked steel wall.

“This is it,” she says.

“This is the exit?” Uri asks.

“There is a door here,” Ava says, telling only half the truth. She feels around on the wall. “But I don't know the mechanism to make it open.”

“There's nothing here.” Ellie paws at the smooth metal.

“It's another test,” Uma surmises.

Ava nods. Uma is right, this has got to be another of her mother's—

Another of Dr. Sara's tests.

What is she missing? She closes her eyes and tries to visualize the layout of the catacomb. Instantly a map is drawn in her mind and it's really nothing: just a single, circuitous corridor. Nonsensical architecture – why would anyone build a structure like this? Two doors on opposite sides of the circle: one leading to the lab and the one which is supposedly located right here and marked 'AVA.' And beyond the door there should be a massive chamber.

And just maybe, she hopes, some answers.

The map she visualizes is a complete, three-dimensional representation and the clarity and ease with which she views and manipulates it is unlike any other thought-form she's ever known. Merely by willing it she causes the map to rotate so she can inspect it from every angle. She zooms in, closer and closer, until she's analyzing the corridor at a molecular level – and curiously what she finds are coordinates with axes x, y, and z. It's as if the entire compound has been plotted on an incredibly precise grid. And when she closely examines the place where the door should be, she finds a message from her mother:

“Good work,” it reads between the innumerable coordinates – or rather Sara seems to speak in her mind, “but only a true Ava may enter the nursery. The door will appear for her double helix alone.”

“Double helix,” Ava mutters, “what does that mean?”

“Like DNA?” Uma suggests.

“That's it.” Ava smiles. “Only a true Ava may enter the nursery.” The others exchange concerned glances. She faces the wall where the door should be, licks her lips, and spits. It splatters against the wall and slides toward the floor.

“Ava?” Ellie's voice is quiet, “you okay, dear?”

And in the next instant there is a quick hiss and the wall slides open and the doorway is dark before them. Ava smiles at the others and raises her eyebrows.

“Let's have a look.”

Stepping through, she enters a chamber as large as an auditorium. It is dim but she can see her breath puffing out in pale clouds. Her eyes struggle to adjust. Her ears detect sounds she associates intuitively with her mother's experiments – wheezing ventilators and electronic beeping. There is no light mounted overhead nor ensconced in the wall but there are shapes and she squints to try and see them better: rows of weird, chrome capsules like the coffins of androids or something space travelers might crawl inside to be frozen asleep for a very long time. And each capsule has an accompanying computer and monitor whose digital readouts cast the room in an eerie green pallor.

Ava creeps forward to the closest capsule. The top half is a clear glass dome, dark but for the reflection of the green digital letters and numbers shown upon the nearby monitor. Ava moves closer. She reaches out to touch the glass—

For some reason she expects to find the rats inside: Socrates and Spartacus.

But instead it's another Ava. It's her! She's looking at herself, lying in the capsule unconscious. Her head is shaved and there are wires inserted into her scalp. Her limbs are atrophied and skeletal, her skin practically translucent like some cave-dwelling amphibian.

“What is this place?” Ellie asks.

And Ava turns to her and the others, frowning:

“It's a nursery.”