“I honestly don’t know,” Pierce said. “Back when the project was still going, there were probably two dozen people in D.C. who had access to its files. These guys could be some of them, or even people hired by them. Whoever they are, they obviously needed help to get the job done. They grabbed me first, because I had the broadest knowledge of the research. Enough for a year’s worth of secret development, down in Station Nine. I’m sure you saw the Cloud Chamber, when you were there. It’s one of only a few in the whole world, and it’s necessary for developing a fog-based weapon. It’s big enough to simulate wide-open space, while also being totally controlled, so you can try different mixtures, different concentrations. There’s a lot of trial and error involved. It took most of a year to retrace my work from the original project. It was only after that point, once it was almost done, that they needed Coleman’s help. He had the expertise on the finishing touches, including the animal testing. We shouldn’t have cooperated with them … but they had ways to force us to do it. Those details I won’t go into. You really don’t want to know about that. It’s enough to know that they succeeded. As of two nights ago, they have a fully working supply of the disease, in three separate canisters. If they escape with them, they could use them anywhere in the world, or sell them to someone else who will. I doubt it would end up being used in a war zone. More likely New York or London or Tokyo.”

A silence fell. Sam thought of the baboon again, and tried to picture a human in the same state. Or thousands of such humans, in some busy public place.

“Christ,” he whispered. He started to say more, but stopped himself. He turned his head, listening. At the edge of his vision, he saw Dani do the same.

The sound they had heard was faint—just audible over the wind in the trees. It sounded like a drumbeat, low and flat and very fast.

An incoming helicopter.

A second later all three of them were turning in circles, scanning the horizon. Dani saw it first; she stopped and pointed almost straight north. Sam followed her gaze and saw a blinking red light, maybe a mile away. The chopper was coming in low—practically hugging the ground.

“Air support?” Sam asked.

“I would say so,” Pierce said. The relief in his voice was palpable.