Gilly, Cricket, and Wendy are hours from campus when a wrong turn takes them deep into the West Virginia mountains. When their car dies on a road that isn't on any map, they find themselves in Hallow's Gap—a coal town that time and the rest of the world seem to have forgotten.

The locals are friendly enough. The sheriff promises a mechanic will look at their car in the morning. The motel has a vacancy. Everyone assures them they'll be on their way as soon as the wind shifts and the fog clears.

But the wind doesn't shift. The fog doesn't clear. And something is wrong with the air.

It tastes like ash and metal and something older. It coats everything in fine gray powder that never stops falling. It gets in their lungs and stays there, and by the second morning, one of them can't stop coughing. What comes up is black.

The town feels emptier than its population suggests. The people they meet seem helpful but hollow, like they're going through motions they've long since stopped understanding. Conversations circle back to the same reassurances: wait it out, the wind will shift, you'll be on your way soon. But no one will drive them out. No one will explain why. And the longer they stay, the more they notice—the strange sounds at night, the way the locals move, the questions that get met with silence, the growing sense that Hallow's Gap isn't a place people pass through.

It's a place people disappear into.

As the air worsens, their stay lengthens, and their window to escape narrows, the girls realize the truth: they were never waiting for repairs. Something in these mountains has been waiting for them. Something patient. Something hungry. Something that breathes through the ash and the coal dust and has been here since long before the first mine shaft was sunk into the rock.

And now it knows they're here.