Eventually she learned to like the feeling that came right before collapse: the way the sky got big, and sounds grew far away and tinny, and all the colors seemed to sharpen to a hallucinatory brightness. There was an intensity of sensation when you were on the edge of what you could handle, when you were physically tested and made to fight for each breath, that was somehow exhilarating.

At the top of the hill, Mal slipped the stainless-steel canteen out of her ruck, her father’s old camping canteen, and filled her mouth with ice water. The canteen flashed, a silver mirror in the late-morning sun. She poured water onto her face, wiped her eyes with the hem of her T-shirt, put the canteen away, and ran on, ran for home.

She let herself in through the front door, didn’t notice the envelope until she stepped on it and heard the crunch of paper underfoot. She stared down at it, her mind blank for one dangerous moment, trying to think who would’ve come up to the house to slide a bill under the door when it would’ve been easier to just leave it in the mailbox. But it wasn’t a bill, and she knew it.

Mal was framed in the door, the outline of a soldier painted into a neat rectangle, like the human-silhouette targets they shot at on the range. She made no sudden moves, however. If someone meant to shoot her, he would have done it—there had been plenty of time—and if she was being watched, she wanted to show she wasn’t afraid.

She crouched, picked up the envelope. The flap was not sealed. She tapped out the sheet of paper inside and unfolded it. Another thumbprint, this one a fat black oval, like a flattened spoon. There was no fishhook-shaped scar on this thumb. This was a different thumb entirely. In some ways that was more unsettling to her than anything.

No—the most unsettling thing was that this time he had slipped his message under her door, while last time he had left it a hundred yards down the road, in the mailbox. It was maybe his way of saying he could get as close to her as he wanted.

Mal thought police but discarded the idea. She had been a cop herself, in the army, knew how cops thought. Leaving a couple thumbprints on unsigned sheets of paper wasn’t a crime. It was probably a prank, they would say, and you couldn’t waste manpower investigating a prank. She felt now, as she had when she saw the first thumbprint, that these messages were not the perverse joke of some local snotnose but a malicious promise, a warning to be on guard. Yet it was an irrational feeling, unsupported by any evidence. It was soldier knowledge, not cop knowledge.