The lighthouse had been dark for three days when Tammi Holloway got the call. Her father, Clinton Brennan, was dead. Heart attack. Found on the rocks at the water's edge with an expression of pure terror on his face—like he'd seen something coming for him. Something he'd been expecting for a long time.

Tammi hadn't spoken to her father in fifteen years. She'd left the lighthouse at eighteen, bitter and confused about why he chose a light that ran itself over his own daughter. Every visit ended the same way: mid-sentence, mid-word, his eyes would go distant, and he'd walk toward the tower.

"I have to tend the light."

Now the light is out. And in her father's journals—hundreds of them, filling her old bedroom—Tammi discovers why.

The first lighthouses weren't warnings to ships. They were temples. Offerings. Constant flames of worship to keep something in the deep satisfied. Something vast and old that had been swimming through voids before our sun ignited. Something that accepts the light as tribute—or, when the light goes out, expects something else.

Tammi's mother didn't drown in an accident. She was taken as an offering when the light flickered out for twenty minutes in 1979.

The light has been dark for three days. Something is stirring in the deep, ancient and hungry, expecting tribute. And Tammi is the last of her line—the last keeper of a compact that predates written history.