It was the great irony of civilization—that in the end it wasn’t a bomb, or terrorism or some other global cataclysm that brought down the curtain on this modern world. It was lack of interest.

They both stood, taking deep breaths, preparing to launch into the frenetic stream of anxious travelers. “Once I get to Brooklyn,” Erica said, “I’m swearing off the friendly skies for good and staying put. Because if I gotta live through the fall of the American Empire, I might as well do it where they never had civilization to begin with.”

Maddy hugged her sister, perhaps for the last time in the foreseeable future, then turned away, forcing her feet in front of her, marching toward her overcrowded gate with disciplined military cadence. Re­fusing, as always, to look back.

The massive vault sat in the cold, seven-story dome of the power plant, a square peg in a round hole. This, reasoned Maddy, was where the plant’s nuclear core would have been, but any machinery had long since been disassembled to make room for this cubic concrete egg in the cold womb of the containment dome. The cube was thirty feet on each side, and the only thing that gave away the fact that it was not solid was a silver titanium vault door on its face—a door which, by the way, was currently wide open. Looking around, Maddy could see no gateway into the dome large enough for this massive, incongruous object to fit through—which meant it must have been built right here.

General Bussard, a slab of a man in both appearance and person­ality, studied her reaction to the cube. “Not what you were expecting, Lieutenant?”

“Just observing, sir,” Maddy answered truthfully. “I didn’t know what to expect.” The cavernous dome was lit dimly from above like the unpleasant half-light of a partial eclipse. The walls around them were filigreed with pipes, conduits and catwalks casting intersecting shadows. Maddy counted four armed guards posted on high catwalks, giving them a full view around the cube. Otherwise there was no one else present. She had anticipated that, whatever the purpose or nature of the installation, there would be swarms of personnel. Their absence did not bode well with her. Neither did the open vault door.