Broke and desperate, paleontologist Grant Coleman gets the chance of a lifetime exploring a long-sealed cave, the fabled home of gigantic creatures. NPS Ranger McKinley Stinson discovers a rancher's prize bull has been butchered by an airborne killer, and tracks the blood trail back to the re-opened cavern. But as she's about to arrest the trespassers, the unstable roof collapses, trapping all. Their only way out is at the cave system's far end. But an eco-system of terrifying mega fauna stands between them and freedom. Death, double-crosses, and a slew of monstrous cave creatures take their toll as the group battles to what they pray is an exit. Will anyone survive this cavern of the damned?