He began to climb. The air was roasting, nearly asphyxiating with the gas of pigeon. Long streaks of guano smeared the walls, encrusting the stairs and banister like layers of paint. The birds seemed to take scant notice of him, fluttering here and there as he made his ascent, as if his presence were no more than a curiosity. Three flights, four; he was panting with exertion, the taste in his mouth and nose was excruciating in its foulness, his eyes stung as if splashed by acid.

At last he reached the top. A final door and, on the wall above it, far out of reach, a tiny window, its edges scalloped by broken glass, yellowed by soot and time.

The door was padlocked.

A dead end. After everything, the girl had led him to a dead end. A furious clang shook the stairwell as the first viral hit the door below him. Birds lifted off and scattered all around him, swirling the air with feathers.

That was when he saw it, so encrusted with guano it had blended invisibly into the wall around it. He used his elbow to smash the glass, then yanked the axe free. A second crash from below. One more push and the virals would be through the door and streaming up the stairs.

Peter lifted the axe over his head and gave it a hard swing, aiming for the padlock. The blade glanced off, but he could tell he’d done some damage. He took a deep breath, calculating the distance, and gave the axe another swing, putting everything he had behind it. A clean hit: the lock split and shattered. He leaned into the door with all his might and with a groan of age and rust it fell open, spilling him into sunlight.

He was on the roof at the north side of the mall, facing the mountains. He hobbled quickly to the edge.

The drop was fifteen meters at least. He’d break his leg or worse.

Lying immobile on the hardpan, waiting for the virals to take him. It wasn’t how he wanted things to end. He was bleeding freely from his elbow; a trail of his blood had followed him from the open door. Though he had no memory of pain, he must have cut it when he’d smashed the panel. But a little blood would hardly make a difference now. At least he had the axe.

He was turning to face the door, preparing to swing, when a cry reached him from below.

“Jump!”

Alicia and Caleb, coming around the corner of the building on horseback, riding fast. Alicia was waving to him, her body arched forward from the stirrups. “Jump!”