They ascended the bank of the river and began to climb. Wherever they were going, he hoped there would be shelter. He didn’t see how they would last the night without it. Never mind the virals; cold like this could kill them just as easily. The important thing was to keep moving. Amy had taken the lead, her strides carrying her up the mountain. It was all Peter could do to keep up. The air felt thin in his lungs; around him the trees were moaning in the wind. After a period of time had passed he looked back and beheld the valley far below them, the river curling through it. They were in shadow now, a zone of twilight, but on the far side of the valley, the faces of the mountains, receding to the north and east, thrummed with golden light. The top of the world, Peter thought, that’s where Amy is taking me. The very top of the world.

The day drained away. In the descending gloom, the landscape appeared as a confusing jumble; what Peter had thought would be the apex of their climb revealed itself to be a crest in a series of ascents, each more exposed and wind-blasted than the last. To the west the mountain fell away sharply, an almost sheer drop. The cold seemed to have reached some deeper place inside him, dulling his senses. It had been a mistake, he realized, to send the horse away. If push came to shove, they could at least have hiked back down and used his body for warmth and shelter. It was a grave thing, to kill such an animal, nothing he could have imagined doing before; but now, as darkness was falling on the mountain, he knew he could have done it.

He realized Amy had come to a stop. He struggled forward and halted at her side, breathing great gulps of air. The snow was thinner here, pushed away by the wind. She was scanning the sky, her eyes narrowed, as if she were listening to some distant sound. Beads of ice clung to her pack, her hair.

“What is it?”

Her gaze settled on the line of trees to their left, away from the open valley.

“There,” she said.

But there was nothing, only the wall of trees. The trees and the snow and the indifferent wind.

Then he saw it: a gap in the undergrowth. Amy was already moving toward it. As they neared, he realized what he was seeing: the gate of a half-fallen fence. It ran the length of the woods on either side of them, entwined with a dense mass of camouflaging vines, now denuded of leaves and covered in snow, making the fence all but invisible, a part of the landscape. Who knew how long they had been walking along it without his noticing. Beyond the opening stood a small hut, more suggestion than actual structure. The building, not more than five meters square, seemed tipped, one part of its foundation having collapsed beneath it; the door stood half open, angled on its hinges. He peered inside. Nothing, only snow and leaves, rivers of rot running down the walls.

He turned. “Amy, where-”

He saw her darting through the trees, away, and lumbered after her. Amy was moving more quickly now, practically running. Through the fog of his exhaustion and the trudge of his frozen feet, Peter had become aware that they had reached the end of their journey, or nearly. Something was leaving him; his strength, stripped away by the cold, was leaving him at last.

“Amy,” he called. “Stop.”

She seemed not to hear him.

“Amy, please.”

She turned to face him.

“What’s here?” he pleaded. “There’s nothing here.”

“There is, Peter.” Her face was lit with joy. “There is.”

“Then where is it?” he said, and heard the anger in his voice. His hands were on his knees; he was panting for breath. “Tell me where it is.”

She lifted her face to the darkening sky, letting her eyes fall shut. “It’s… everywhere,” she said. “Listen.”

He did his best; with every ounce of his remaining strength he sent his mind outward. But all he heard was the wind.

“There’s nothing,” he said again, and felt his hopes collapsing. “Amy, there’s nothing here.”

But then he heard it.

A voice. A human voice.

Somebody, somewhere, was singing.

• • •

They saw the beacon first, rising in the trees.

They had come into a clearing, the forest parting. All around them Peter could discern evidence of human habitation, the suggestive shapes of ruined buildings and abandoned vehicles under the snow. The antenna stood at the edge of a wide depression in the earth, full of debris-a foundation of some kind, for a building long since gone. The antenna was positioned to the side of it, a four-legged metal tower rising high above them, anchored in place by steel cables sunk in concrete. Affixed to its apex was a gray orb studded with spikes. Beneath the orb, encircling the tower and jutting from the sides like the petals of a flower, was a series of paddle-like objects. Perhaps these were solar panels; Peter didn’t know. He placed a hand on the cold metal. Something appeared to be written on one of the struts. He brushed the snow aside, revealing the words UNITED STATES ARMY CORPS OF ENGINEERS.

“Amy-”

But the place beside him was empty. He detected movement at the edge of the clearing and quickly followed her, into the underbrush. The sound of singing was stronger now. Not words but a wash of notes in phrased patterns, rising and falling. It seemed to be drifting toward them from all directions on the wind. They were close now, very close. He sensed the presence of something up ahead, an openness. The trees separating, the sky exposed. He reached the place where Amy stood, and then stopped.

It was a woman. She was facing away, standing in the dooryard of a small log house. The windows of the house were lighted, and curls of smoke coiled from the chimney. She was shaking out a blanket; more blankets sagged on a line that stretched between a pair of trees. The incredible thought reached him that this woman, whoever she was, was taking in her laundry. Taking in her laundry and singing. The woman was wearing a heavy woolen cloak; her hair, dense and dark with streaks of snowy white, flowed over her shoulders in a cloudlike mass. The lines of her bare legs descended from the edge of the cloak to her feet, on which she appeared to be wearing nothing more than a pair of rope sandals, her toes in the snow.

Peter and Amy moved toward her, the words of her song resolving as they approached. Her voice had a rich, full-throated sound to it, full of a mysterious contentment. She sang and went about her work, placing the blankets in a basket at her feet, apparently oblivious to their presence. The two of them were standing just a few meters behind her now. Sleep, my child, and peace attend thee, the woman sang,

All through the night.

Guardian angels God will send thee,

All through the night.

Soft the drowsy hours are creeping,

Hill and dale in slumber sleeping,

I my loved ones’ watch am keeping,

All through the night.

She halted, her hands poised over the line.

“Amy.”

The woman turned. She had a broad, handsome face and dark skin, like Auntie’s. But it was not an old woman he saw. Her skin was firm, her eyes clear and bright. Her face bloomed with a radiant smile.

“Oh, it is good to see you.” Her voice was like music, as if she were singing the words. She advanced toward them on her sandaled feet and took Amy by the hands, holding them with a maternal tenderness. “My little Amy, all grown up.” She let her eyes drift past Amy toward Peter, appearing to notice him for the first time. “And here he is, your Peter.” She gave her head a little shake of wonder. “Just as I knew he would be. Do you remember, Amy, when I said to you, Who is Peter? It was when I first met you. You were very small.”

Tears had begun to fall from Amy’s eyes. “I left him.”

“Hush now. It is as it had to be.”

“He told me to run!” she cried out. “I left him! I left him!”