“Okay. Now, do you remember what to do if something happens to me?”

“Hunker down in the med ward with Emanuel and the kids, and shoot anything that moves.”

“You got it,” Bouma said, grinning.

Holly fixated on the man’s crooked teeth. For a second, they reminded her of the sharp teeth lining the jaws of every Organic she had seen.

“Can you give me a hand with this?” Bouma asked as he started climbing the ladder. She gripped the ladder tightly, and watched the Marine reach for the vent cover. “I guess this means we have to postpone our walk.”

“Yeah, but it will give me something to look forward to,” he said, hoisting himself into the duct and staring into the pitch-black tunnel. A sudden chill of fear gripped him, and for a moment he had second thoughts about clearing the vents. He peered back down and saw Holly’s wide eyes staring up at him. She smiled, and the fear faded. He had a mission to finish, a squad to avenge, and a group of civilians to protect. And, best of all, a pretty girl waiting for him.

“Good luck,” she said as Bouma’s feet disappeared in the darkness.

The trip back to the train was painfully slow, providing Sophie with plenty of time to think. With Secundo Casu gone, her hope of seeing Mars was dead, and her hope for survival had diminished considerably. With every step she grew more anxious to get back to the Biosphere—back to Emanuel and the rest of her team.

By the time she reached the train, she had accepted the fact that the facility was her home for the foreseeable future. But was it really all that bad? The death toll worldwide could very well be in the billions, an unfathomable number. The Biosphere had virtually everything they needed to support their little band of survivors, and it was, to her knowledge, the safest place to ride out the invasion.

“Wow, cool,” David said as they rounded the last corner and the train came into view. “We get to ride on that?”

Overton hushed him with a finger. “Quiet, kid.”

The boy ignored him and rushed toward the automatic doors of the first cabin.

“Wait up,” Jeff shouted after him.

Their voices echoed off the concrete tunnel walls. Sophie smiled as Jeff chased his brother onto the platform, stopping him before he could enter the train. The boys wrestled playfully at the doors, David squirming in his brother’s grasp.

A shadow danced across their path.

Overton saw it at the same moment Sophie did. She froze, her stomach tightening as the blue glow washed over the dimly lit tunnel.