For six days, a Marine Reserve, a Navy survival instructor and an engineer battle isolation, hallucination and starvation as they struggle to escape an abandoned Cold War fallout shelter 240 feet underground in California's Mojave Desert.
A firefighter-training officer, a retired bomb technician and a former Green Beret spend six days in complete darkness fighting to find the exit of a treacherous cave system deep underneath the Ozark Mountains. Isolation, hallucination, dangerous accidents and hordes of snakes complicate the mission.