“You mean there’s no real threat? This was just practice?”

He pauses in his descent to look up at me. “Make no mistake, the threat is real. The Underground is in constant danger.” He throws a wry smile up at me. “After all, we’re at war.”

AFTER AN EARLY communal supper of simple but delicious food served by the children (trying, and failing, to look very serious), I go immediately to bed. With the mission to find the cybersurgeon waiting for me the next night, I think I’ll have trouble falling asleep so early. On the surface it would be nearly dark, and down here the ceiling panels are mimicking a gentle orange sunset that shines through the camphor tree boughs as I wearily make my way to my chamber.

I shut the door—it has no lock, which is worrying, but I suppose there’s no danger down here, except from the outside, the Above, as they call it. I fall into bed, expecting to stare sleeplessly at the ceiling. But I must fall asleep almost immediately, because the next thing I know I’m in another place.

Part of me knows it is a dream, but somehow that doesn’t make it any less disturbing. I’m walking through a meadow of flowers and tall grass. I can see it. I can smell the green scent that rises as I crush the herbs beneath my feet. It feels completely real. Up ahead I see shapes, low to the ground, and I approach, smiling, thinking they might be animals.

The stench hits my nose just before I can make out what they are. Corpses, human corpses, scattered across the beautiful meadow, their limbs twisted and contorted, their faces twisted in final agony and frozen in place until their flesh rots. Which it is definitely starting to. The scent of the flowers turns sickly, too sweet, and then dissolves into a smell of blood and decay.

At first I can see the grasses beneath the bodies. But as I walk—and because it is a dream, I can’t stop walking, can’t weep, or run away—the bodies grow thicker on the ground until it seems as if the Earth itself is sprouting them from the dirt. A crop of human corpses.

I forge my way through, almost wading, until the bodies are piled on top of one another and I have to step high, then climb, and finally crawl up a mountain of bodies. Their rotting flesh sloughs off beneath my fingers as I scramble upward. I can’t stop, because there’s someone standing atop this mountain of the dead. A tall, slender man with dark hair, a neatly trimmed goatee. I know I have to reach him.

He looks down at me, and his eyes are so gentle. How can that be, when he’s standing on ten thousand corpses? Corpses he made. Because of course, the man is Aaron Al-Baz.

He reaches out a hand as if to help me to the summit, but I hold back. He tilts his head, looking at me curiously, and says, “Extinction is natural.”

This wasn’t a natural extinction, I want to say, but in my dream I’m mute.

“Humans evolved to the point where they could wipe themselves off the face of the Earth,” he says in that soft, reasonable voice. “They would have, eventually. It was just a question of how many other species they took with them. My way was best.”

Dream Me manages to shake her head.

“It was a hard thing to do,” he says, a shade of sorrow crossing his face. “But the right thing. You will see, in time.”

Unable to resist, I reach for his hand. But instead of pulling me up to the summit he shoves me violently backward and I’m tumbling, cartwheeling over the pile of bodies, landing in a tangle, trapped in a net of corpses that pull me under like quicksand . . .

I wake up screaming!

I’m out of bed and down the hall before I really know if I’m awake or still asleep. No one wakes, no one peers out of their bedrooms. The solid rock must have shielded the sound of my screaming.

I could go to Flint. He’s the leader, he’s responsible for all of these people, and for me now. I should tell him what I know. I could go to Iris, let her take me in her plump maternal arms and comfort me as if I were one of her brood of second children.

But instead I go to Lachlan. I’m drawn to him, irresistibly, in my moment of need.

He showed me where his room is, in passing, as he was giving me a tour of the Underground, but he didn’t invite me in. His room is one of the few occupied dwellings on the upper story of galleries. As I race up the stairs I realize that if the Eden authorities ever found this place and launched an attack, Lachlan would be first in the line of fire. Of course, he would also be the first one with a clear shot at the invaders. Knowing him (and strangely, I almost feel as if I do), he probably thought of both when picking his room. He would be either a shield, or a sacrifice for the vulnerable second children he was defending down below. Whatever was required, he would do.

I pound on his door. I don’t have the composure for a polite knock. Almost instantly the door opens a crack and I see not his face, but the muzzle of his weapon, the glint of his eye barely visible behind it.

The first words out of his mouth are “What’s wrong?” He opens the door another inch and looks beyond me for danger.

“I . . . I had a nightmare,” I confess.

He visibly relaxes, and I wonder if he looks a little disappointed in me. Like he expected me to be able to get through something as trivial as a nightmare on my own. He doesn’t realize it is so much more—a nightmare about a terrible truth.

He pushes the door open with a sigh. “I’m not sleeping anyway. You might as well come in.”

Somehow I expect his room to be stark and ascetic: bare walls and weapons. But it’s like nothing I imagined. Standing racks of clothes are almost decorations in themselves. I realize they’re costumes, the disguises he uses to move freely around the city. The bright colors of inner circle fashions dominate, muted here and there by various uniforms—of reclamation workers, deliverymen, and other Eden workers who could pass virtually unnoticed. I even see the collection of pieced-together rags that made up his hobo disguise, complete with false hair and beard.

But it is the walls that are the most surprising. Every square inch is covered in artwork. Mesmerized, I move closer to look. Most of the pictures are obviously drawn by children, bold and colorful depictions mostly of small grinning little stick people holding the hand of a tall stick man obviously meant to represent Lachlan. Without exception, the balloon-headed Lachlans the kids draw wear huge smiles.

Though the kids’ drawings dominate, there are other more skilled and subtle works, too. One is a simple pencil sketch of an elderly woman sitting in a kitchen, a lump of dough on the table before her. The lines are sparse but evocative. I can almost smell bread baking. In one corner is the title, Nana. In the other is the artist’s name: Iris. I can see Iris’s life all in an instant—raised by a beloved grandmother, bereft and alone when her grandmother died. And now she’s here, grandmother herself to a huge family. Why did she give this drawing to Lachlan? To remind him that everyone here is family?