A group of friends investigates the mystery of a strange staircase in the woods in this mesmerizing horror novel from the New York Times bestselling author of The Book of Accidents.

Five high school friends are bonded by an oath to protect one another no matter what.

Then, on a camping trip in the middle of the forest, they find something a mysterious staircase to nowhere.

One friend walks up—and never comes back down. Then the staircase disappears.

Twenty years later, the staircase has reappeared. Now the group returns to find the lost boy—and what lies beyond the staircase in the woods. . . .