She fired.

A mist of red, a confusion of bodies tumbling, the rifle clattering away. In the time it took Peter to realize that Alicia was not dead, she was on her feet again. The viral lay where he’d come to rest, the back of his head cratered with blood. She’d shot it through the mouth. Above them, the other two had come to an abrupt halt, stiffening, teeth flashing, their heads swiveling toward Alicia as if pulled by a single string.

“Get out of here!” she called, and vaulted over the counter. “Just run!”

He did. He ran.

He was deep inside the mall now. There seemed to be no way out. All the exits were barricaded, blocked by mountains of debris: furniture, shopping carts, dumpsters full of trash.

And Theo, his brother, was gone.

His only option was to hide. He tore down a hall of shuttered storefronts, yanking upward at their grates, but none would open; all were locked tight. Through the fog of his panic, a single question emerged: Why wasn’t he dead yet? He had fled from the atrium not expecting to make it more than ten steps. A flash of pain and it would all be over. At least a full minute had passed before he’d realized the virals weren’t pursuing him.

Because they were busy, he thought. He had to clutch one of the grates just to keep standing. He dug his fingers between the slats and pressed his forehead against the metal, fighting for breath. His friends were dead. That was the only explanation. Theo was dead, Caleb was dead, Alicia was dead. And when the virals were done, when they had drunk their fill, they’d be coming for him.

Hunting him.

He ran. Down one hall and into another, tearing past shuttered storefront after shuttered storefront. He wasn’t even bothering with the grates now; his mind was seized with one thought: to get outside, onto open ground. Daylight ahead, and a feeling of openness: he turned a corner and emerged, skidding on the tiles, into a wide, domelike space. A second atrium. The area was clear of debris. Sunshine descended in smoky shafts from a ring of windows, high above.

In the center of the room, standing motionless, was a herd of tiny horses.

They were grouped in a tight circle beneath some kind of freestanding shelter. Peter froze, expecting them to scatter. How had a herd of horses gotten into the mall? He stepped cautiously forward. Now it was obvious: the horses weren’t real. A carousel. Peter had seen a picture of one, in a book in the Sanctuary. The base would turn and music would play, and children would ride the horses around and around. He stepped onto the decking; a heavy layer of dust encased them, dulling their features. He squared his shoulders to one of the animals and brushed the grime away, revealing the bright colors beneath, the precisely painted-on details: the lashes of its eyes, the grooves of its teeth, the long slope of its nose and the flaring nostrils.

He felt it then, a sudden awareness at his extremities, like a touch of cold metal. He startled, lifting his face.

Standing before him was a girl.

A Walker.

He couldn’t have said how old she was. Thirteen? Sixteen? Her hair was long and dark, and thick with mats; she was wearing a pair of threadbare gaps cut off at the ankles and a T-shirt stiff with dirt, all of it too large on her boyish frame. Her pants were cinched to her waist with a length of electric cord; on her feet she wore a pair of sandals with plastic daisies poking between the toes.

Before Peter could speak, she raised a finger to her lips: Don’t speak. She moved briskly toward the center of the platform and turned to wave him on, to tell him to come with her.

He heard them then. A skittering in the hall, the rattle of metal grates on the shuttered storefronts.

The virals were coming. Searching. Hunting.

The girl’s eyes were very wide. Hurry, her eyes said. She took his hand and pulled him to the center of the platform. There she dropped to her knees and dug at a metal ring in the floor. A trapdoor, flush with the wooden decking. She climbed inside so that only her face was showing.

Quickly, quickly.

Peter followed her down the hole and sealed the trapdoor above him. They were under the carousel now, in some kind of crawl space. Angled blades of light, spangled with dust motes, fell through the slats of the decking over their heads, revealing a dark bulk of machinery and, on the floor beside it, a rumpled bedroll. Plastic bottles of water and tins of food stacked in rows, their paper labels long since worn away. Did she live here?

The decking shuddered. The girl had dropped to her knees. A shadow moved across them. She was showing him what to do.

Lie down. Be still.

He did as she asked. Then she climbed on top of him, onto his back. He could feel the heat of her body, the warmth of her breath on his neck. She was covering his body with her own. The virals were all over the carousel now. He could feel their minds searching, probing, hear the soft clicking in their throats. How long before they discovered the trapdoor?

Don’t move. Don’t breathe.

He closed his eyes tightly, willing himself into absolute stillness, waiting for the sound of the door being ripped off its hinges. The rifle was on the floor beside him. He might get off a shot or two, but that would be all.

Seconds passed. More shudders above, the sharp, excited breathing of virals with human scent in their nostrils. Tasting the blood in the air. But something was wrong; he sensed their uncertainty. The girl was pressing down upon him. Screening him, protecting him. Silence from above; had the virals gone? A minute moved by, and then another. His sense of expectation shifted from the virals to what the girl would do next. At last she climbed off him. He rose to his knees. Their faces were just inches apart. The soft curve of her cheek was like a child’s, but her eyes were not, not at all. He could smell her breath; there was something sweet to it, like honey.

“How did you-”

She shook her head sharply to silence him, pointing to the ceiling, then pressed her fingers to her lips again.

They’re gone. But they’ll be back.

She rose to her feet and opened the trapdoor. A quick turn of the head to show him her meaning.

Follow me. Do it now.

They emerged onto the decking of the carousel. The room was empty, but he could feel the virals’ departed presence, the air swirling in unseen eddies around the places they had stood. Moving quickly, the girl led him to a door across the atrium. It was propped open, held in place with a wedge of concrete. They stepped inside and she let the door close behind them, sealing them inside; he heard the click of a lock.

Blackness.

A new panic gripped him, a feeling of complete disorientation. But then he felt her taking his hand. Her grip was tight, meant to reassure; she pulled him farther in.

I have you. It’s all right.

He tried to count his steps, but it was useless. He could feel in her grip that she wanted him to go faster, that his uncertainty was holding them back. He stumbled on something in his path and the rifle fell away, lost in the darkness.

“Wait-”

A wang from behind, and the groan of bending metal. The virals had found them. Ahead he detected a glow of daylight; his surroundings began to emerge to his vision. They were in a long, high-ceilinged hallway; slims were shoved against the walls, a chorus of grinning skeletons, their limbs contorted in what seemed to be postures of warning. Another crash from behind; the door was failing, caving in on its hinges. The hallway ended at another door, which stood open. A stairwell. From high above came a glow of yellow daylight, and the sound and smell of pigeons. On the wall was a sign: ROOF ACCESS.

He turned. The girl was still standing in the hallway, just outside the stairwell door. Their eyes met briefly, hauntingly. Before another second passed, the girl stepped forward and, rising on her toes, pressed her closed mouth-a bird pecking water-against his face.