Maeve Martin arrives at the High Water Center for the Arts, a gorgeous lodge nestled deep in the Rocky Mountains, determined to do one thing: begin her own dance company. A retired performer and mother of two, time is running out for her to find her feet again after the collapse of her disastrous—and violent—marriage. And at first, there's a thrill to being on her own for the first time in years. Isolated in the snowy beauty of the retreat, Maeve can forget the ghost of her past for an hour, for a day.

But when an avalanche strikes, Maeve finds herself trapped with six other guests. They’ve lost all power, phone service, heat, and the road back to town. At first, there’s a sense of camaraderie—the fire is warm, the freezer well-stocked. But as the days pass and the storm rages on outside, tensions start to run high. Help is coming, so they just have to hold on, right?

Then the first guest meets an unspeakable death.

Followed by another.

Soon Maeve must admit how little she knows about these strangers . . . and how useless a locked door is if the darkness is already inside.