Two high level scuba-divers and long-time friends, Don and Dave, broke a world record for depth in the Boesmansgat cave in South Africa. It would take them 15 minutes to reach the bottom, but 12 hours to surface. Having reached the bottom, against all odds, they find a body. They decide to come back and retrieve it. They call the parents, enrol 8 fellow divers, and hire a cameraman to document the dive. The camera will follow them throughout the preparation and the dive, including to the bottom of the cave. Little did they know that on that historic dive, Dave would not be coming back. In...