And then the first viral fell, a blur of movement first above and then behind them, dropping through the atrium roof; Peter rolled in time to see Theo being lifted up, tossed toward the ceiling, his rifle dangling where the sling had tangled in his arm, his hands and feet scrabbling at space. A second viral, hanging upside down from one of the ceiling struts, snatched Peter’s brother by the ankle as if he weighed nothing at all. Theo’s body was fully inverted now; Peter saw the look on his brother’s face, an expression of pure astonishment. He’d made no sound at all. His rifle fell away, spinning to the floor below. Then the viral flung Peter’s brother through the open roof and he was gone.

Peter scrambled to his feet, his finger finding the trigger. He heard a voice, his voice, calling his brother’s name, and the sound of Alicia firing. Three virals were on the ceiling now, launching from strut to strut. Peter detected, at the periphery of his vision, Alicia shoving Caleb up and over the counter of a restaurant on the far side of the atrium. Peter fired at last, fired again. But the virals were too fast; always the spot where he aimed was empty. It seemed to Peter as if they were playing a kind of game, trying to trick them into expending their ammunition. Since when do they do that? he thought, and wondered when he’d heard these words before.

As the first one let go, Peter saw, in his mind’s eye, the fatal dimension of its arc. Alicia was standing with her back to the counter now. The viral descended straight for her, arms outstretched, legs bent to absorb the impact, a being of teeth and claws and smoothly muscled power. In the instant before it landed, Alicia stepped forward, positioning herself directly under it, holding the rifle away from her body, like a blade.

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.