“Mira,” Peter said, trying to pull her free, “please.”

Still she held on. “I can’t, I can’t, I can’t.”

From below, a clawed hand reached up, wrapping around her ankle. “Poppa!”

Then she was gone.

There was nothing else he could do. Peter dashed toward the gap, took it at a leap, and dropped through the hatch behind Caleb. He told Michael to hold the train steady and swung open the door to the cabin and looked aft.

The virals were all over the third boxcar now, clinging to the sides like a swarm of insects. So intense was their frenzy that they appeared to be fighting with one another, snapping and snarling for the right to be the first ones inside. Even over the wind, Peter could hear the screams of the terrified souls inside.

Where was the Humvee?

Then he saw it, racing toward them at an angle, bouncing wildly over the hardpan. Hollis and Olson were clinging to the vehicle’s roof. The big gun was depleted, all its ammo spent. The virals would be all over them any second.

Peter leaned out the door. “Bring it closer!”

Sara gunned the engine, drawing alongside. Hollis was the first to grab the ladder, then Olson. Peter pulled them through into the cab and called down, “Alicia, you go!”

“What about Sara?”

The Humvee was drifting away again, Sara fighting to keep them close without colliding. Peter heard a crash as the door of the last boxcar was ripped away, tumbling end over end into the receding darkness.

“I’ll get her! Just grab the ladder!”

Alicia jumped from the roof of the Humvee, hurling her body across the gap. But the distance was suddenly too great; in his mind Peter saw her falling, her hands grabbing at nothing, her body tumbling into the crushing rush of space between the vehicles. But then she had done it; her hands had found the ladder, Alicia was climbing hand over hand up the train. When her feet reached the bottom rung, she turned, stretching her body into the gap.

Sara was gripping the wheel with one hand; with the other she was frantically trying to wedge a rifle into place to brace the gas pedal.

“It won’t stay!”

“Forget it, I’ll grab you!” Alicia called. “Just open the door and take my hand!”

“It won’t work!”

Suddenly Sara gunned the motor. The Humvee shot forward, pulling ahead of the train. Sara was on the edge of the tracks now. The driver’s door swung open. Then she hit the brakes.

The edge of the train’s plow caught the door and sheared it off like a blade, sending it whirling away. For a breathtaking instant the Humvee rocked onto its two right wheels, skidding down the embankment, but then the left side of the vehicle banged down. Sara was moving away now, rocketing across the hardpan at a forty-five-degree angle to the train; Peter saw a skid in the dust and then she was pulling alongside again. Alicia stretched a hand out into the gap.

Peter: “Lish, whatever you’re going to do, do it now!”

How Alicia managed it, Peter would never fully comprehend. When he asked her about it later, Alicia only shrugged. It wasn’t anything she’d thought about, she told him; she had simply followed her instincts. In fact, there would come a time, not much later, when Peter would learn to expect such things from her-extraordinary things, unbelievable things. But that night, in the howling space between the Humvee and the train, what Alicia did seemed simply miraculous, beyond knowing. Nor could any of them have known what Amy, in the engine’s aft compartment, was about to do, or what lay between the engine and the first boxcar. Not even Michael knew about that. Perhaps Olson did; perhaps that was why he’d told Peter to take his daughter to the engine, that she’d be safe there. Or so Peter reasoned in the aftermath. But Olson never said anything about this, and under the circumstances, in the brief time they had left with him, none of them would have the heart to ask.

As the first viral launched itself toward the Humvee, Alicia reached out, snatching Sara’s wrist off the steering wheel, and pulled. Sara swung out on Alicia’s arm in a wide arc, separating from the vehicle as it swerved away. For a horrible instant her eyes met Peter’s as her feet skimmed the ground-the eyes of a woman who was going to die and knew it. But then Alicia pulled again, hard, drawing her upward, Sara’s free hand found the ladder, and the two of them were climbing; Sara and Alicia were up and rolling into the cab.

Which was when it happened. An earsplitting boom, like thunder: the engine lurched violently forward, free of its weight; everything in the cab was suddenly airborne. Peter, standing by the open hatch, was slapped off his feet and hurled backward, his body slamming into the bulkhead. He thought: Amy. Where was Amy? And as he tumbled to the floor he heard a new sound, louder than the first, and he knew what this sound was: a deafening roar and a screech of metal, as the cars behind them jumped the rails, jackknifing into the air and careering like an avalanche of iron across the desert floor, everyone inside them dead, dead, dead.

They came to a stop at half-day. The end of the line, Michael said, powering down. The maps Billie had shown them indicated that the rails petered out at the town of Caliente. They were lucky the train had taken them this far. How far? Peter asked. Four hundred kilometers, give or take, said Michael. See that mountain ridge? He was pointing through the slitted windshield. That’s Utah.

They disembarked. They were in some kind of railyard, with tracks all around, littered with abandoned cars-engines, tankers, flatbeds. The land here was less dry; there was tall grass growing, and cottonwoods, and a gentle breeze was blowing, cooling the air. Water was running nearby; they could hear the sound of birds.

“I just don’t get it,” Alicia said, breaking the stillness. “Where did they hope to get to?”

Peter had slept in the train, once it was clear no virals were pursuing them, and awakened at dawn to find himself curled on the floor beside Theo and Maus. Michael had stayed up through the night, but the ordeal of the last few days had eventually caught up with everyone. As for Olson: perhaps he’d slept, though Peter doubted it. The man had spoken to no one and was now sitting on the ground outside the engine, staring into space. When Peter had told him about Mira, he hadn’t asked for any details, just nodded and said, “Thank you for letting me know.”

“Anywhere,” Peter answered after a moment. He wasn’t sure what he was feeling. The events of the night before-the whole four days at the Haven-felt like a feverish dream. “I think they just wanted to get… anywhere.”

Amy had stepped away from the group, into the field. For a moment they watched her, moving through the windblown grass.

“Do you think she understands what she did?” Alicia asked.

It was Amy who had blown the coupler. The switch was located in the rear of the engine compartment by the head-end unit. Probably it had been connected to a drum of diesel fuel or kerosene, Michael surmised, with some kind of igniter. That would have been enough to do it. A fail-safe, in case the cars were overrun. It made sense, Michael said, when you thought about it.

Peter supposed it did. But none of them could explain how Amy had known what to do, nor what had led her to actually throw the switch. Her actions seemed, like everything else about her, beyond ordinary understanding. And yet it was because of her, once again, that they were all alive.

Peter watched her for a long moment. In the waist-high grass she appeared almost to float, her hands held out from her sides, grazing the feathered tips. Many days had passed since he’d thought of what had happened in the Infirmary; but watching her now as she moved through the grass, he was washed by the memory of that strange night. He wondered what she had told Babcock when she had stood before him. It was as if she were part of two worlds, one that he could see and one that he could not; and it was within this other, hidden world that the meaning of their voyage lay.