Three teenage girls splash in the lake on a sweltering summer evening. Shiloh, Kat, and Ruth are unaware of the man who spies on them from the woods. They have no idea how their lives will be changed by the brutal violence that follows--and the vow of secrecy they take. Fifteen years later, Ruth and Shiloh have both returned to Prairie Creek, Wyoming, where Kat is deputy sheriff. Though they've tried to leave their shared past behind, each has the feeling that someone is lurking in the shadows. When a local girl vanishes, Kat is convinced there's a connection to that long ago night. But as the friends unite to find the missing teenager, a killer sends a chilling message.