Kira took the first watch, talking softly to Bobo as he nibbled on an overgrown planter box. Afa was still working when Heron took over at two in the morning, but when Kira woke up at seven he was asleep in his chair, slumped down over the darkened screen. Kira couldn’t help but wonder if he’d fallen asleep naturally, or if Heron had somehow knocked him unconscious.

They packed up and rode out, following the map and discovering that Heron was right, and the highway was elevated. They passed through mile after mile of Chicago as if on a bridge through a swamp, looking down at houses and parks and schoolyards all flooded and soggy, the oily surface of the water glinting brightly in the morning sun. Here and there a river moved through the city, evidence of an extremely high water table, and Kira marveled that the city had ever been dry at all. It must have taken an immense effort for the old world to keep the lake and the rivers and even the groundwater in check. Part of her felt proud, as Afa had been the day before, smiling to think that she was a part of such an amazing legacy—a species so intelligent, so capable and determined, that they could hold back the sea and turn rivers around in their paths. To have taken this marshy coastline and turned it into a megacity was a feat to be proud of.

Another part of her thought only of the towering pride. How easy would it be for a civilization so amazing to reach just a little too far? To do something it shouldn’t? To make one sacrifice or one compromise or one rationalization too many? If you can build a city so great, what’s to stop you from building a person? If you can control a lake, what’s to stop you from controlling a population? If you can subjugate nature itself, why should a sickness ever get out of hand?

Kira thought about the Trust: about all their secret plans and hidden intentions. About the Failsafe. What was it? Were they trying to save the world, or destroy it? The answers were in the data center, and the data center was in their grasp.

They followed Interstate 90 on a straight course northwest, until at last it arced farther west to join 94. To their dismay it began to dip down here, not just losing its elevation but literally running below the level of the rest of the city—not under the ground, but sunken into it. What had once been a highway was now a lazy river, with only the tops of the tallest trucks poking out above the water.

“We’ll need to double back,” said Samm.