Point Bluff is the perfect place for hiking, rock climbing and cave exploring. But hidden inside one of the Montana caves is a deadly virus of unknown origins. When this virus attacks, it wipes out nearly all of Point Bluff's 10,000 townspeople, leaving almost no trace and no clues as to their disappearance.

The survivors find each other and try to flee, but they soon discover they are trapped. No one is safe, and no one immune, when even they start dying mysterious deaths.