Some things belong in the dark.
Search and rescue expert Cal Cintron retreated to the rugged backcountry of the Elkhorn Mountains to escape the ghosts of his past. But when a group of hikers vanishes near an abandoned, restricted section of the wilderness, Cal is forced to face the one thing that terrifies him most: going underground.
The missing hikers aren't just lost. They stumbled into a breathing, ancient abyss that shouldn't exist-and woke something that has been waiting in the shadows since the Ice Age.
Now, Cal and the remaining survivors are trapped in a claustrophobic subterranean maze, relentlessly hunted by a massive, pale-furred apex predator that science claims died out twelve thousand years ago. This beast is fast, intelligent, and fiercely territorial. As their resources dwindle and the structural integrity of the earth fails around them, Cal must push through the darkness to lead the group to the surface.