A young couple's dream of starting a family shatters as they descend into the depths of paranoia and must struggle to survive an evil presence that wants nothing more than their very own lives.

The story of a family struggling to survive in a world terrorized by a deadly, primeval species who have evolved for millions of years in the pitch darkness of a vast underground cave system, hunting only with their acute hearing. As the family seeks refuge in a remote haven where they can wait out the invasion, they start to wonder what kind of world will remain when they're ready to emerge.