Claire Bennett zipped up her son's hoodie — a bright red one with a spider stitched across the chest — and laughed as four-year-old Ethan spun in a circle, arms out like he could actually shoot webs from his wrists. "Ready, little hero?" she asked. Ethan nodded so hard his blond curls bounced.

Beside them, a German Shepherd named Titan sat perfectly still, ears swiveling at every sound in the trees. He wasn't an ordinary family dog. Titan had spent three years as a certified protection K9 before a line-of-duty injury retired him early. Claire's brother, a police sergeant, had insisted she take him home. "He'll never stop watching," he'd told her. "It's what he's built for."

The three of them set off down the gravel path into Grayfield Woods, the late autumn air sharp and gray, dead leaves crunching underfoot. Ethan chattered about spiders and superheroes, occasionally darting ahead to inspect a mushroom or a beetle, and every time he did, Titan's whole body tensed until the boy circled back.

Claire barely noticed at first, but Titan had started walking differently. His head was low. His ears were locked forward, not on Ethan, but on the treeline to their left. A soft, steady growl rumbled in his chest, so quiet Claire almost mistook it for the wind.

"Titan? What is it, buddy?" She scanned the woods and saw nothing but bark and shadow. Still, the dog's hackles rose in a stiff ridge along his spine.

Ethan, oblivious, crouched by the trail to examine a pile of orange leaves. "Mommy, look! A whole leaf mountain!"

"Careful, sweetie, don't wander—"

A branch snapped, too close, too deliberate. Titan spun toward the sound so fast his leash nearly tore from Claire's hand. Fifty yards off, half-hidden behind a birch trunk, a man stood watching them. He wore a flannel shirt, unbuttoned over a dark shirt, and he did not move like someone out for a walk. He simply stood, and stared, and did not look away when Claire's eyes met his.

"Ethan, come here, honey," Claire said, keeping her voice light even as her pulse jumped. Ethan skipped back to her side, and she scooped his small hand into hers. Titan positioned himself between the family and the stranger without being told, a wall of amber-eyed muscle.

When Claire looked again, the man was gone.

She told herself it was nothing — a hiker, a birdwatcher, someone as startled by them as she was by him. But Titan didn't relax. Not for the rest of the walk. He stayed pressed against Ethan's leg, nose lifted to the wind every few seconds, reading a story in the air that Claire couldn't see.

She didn't know yet that the man's name was Marcus Doyle, that he had been watching her family for six days, or that in less than an hour, only one animal on that trail would decide whether Ethan came home.