But Dryden was already doing the math. The distance to the vehicles—easily a quarter mile to the nearest of them. The time before the drones arrived—seconds now. Whatever was in the canisters, the air in this forest was going to be saturated with it long before anyone reached the safety of the motorcade.

Grace kept shouting, looking around for his people, like a shepherd. Maybe he knew it was hopeless—he had to know—but he wasn’t giving up. Dryden admired that, though it changed nothing: these people were not going to make it. The whine of the drones was almost on top of them now.

Without breaking stride, Dryden took Danica’s hand and veered hard to the right, northeast while the others ran northwest.

“Come on!” he said.

“What are you doing?”

“You’ll see.”

She made no attempt to pull away. They sprinted together, ducking low limbs and boughs, the FBI people already lost to sight.

Then Dryden heard a sharp metallic impact, like a saucepan landing on concrete, somewhere far to his left. From the same direction, voices cried out, full of alarm. The sound came again a second later, not far from the first.

Then something came skittering down through the canopy just fifty feet to Dryden’s right. It thudded dully into the dirt, kicking up dead leaves and needles. Dryden turned his head as they sprinted; he caught a glimpse of a red metal tank the size of a beach ball, with a black valve assembly attached. An instant later, thick white vapor began surging from it under pressure. In a matter of seconds the cloud was twenty feet across and growing, carried on the steady breeze that blew among the tree trunks.

Dryden faced forward again. Beside him, Danica was looking around, too.

“It’s everywhere,” she said.

A dense screen of pines extended across their path, dead ahead. Dryden hoped like hell he was right about what lay beyond. They crashed through the boughs without stopping—and saw the tilted yellow Escort fifty feet ahead of them.

Dryden sprinted harder as they crossed the last of the distance; he let go of Danica and reached the vehicle two steps ahead, slamming to a stop against it. He pulled the handle, took hold of the door and hauled it upward, stepping back and clearing the way for her to get past him. She was already there, reaching up and in, grabbing onto whatever she could and hoisting herself into the car. As she did, Dryden risked a look over his shoulder: the white gas had already enveloped the screen of pine trees.