From executive producer James Cameron (Avatar) comes a thrilling underwater adventure based on true events. Master diver Frank McGuire leads a team—including his 17-year-old son—to explore the largest, most beautiful and least accessible cave system on Earth. But when a tropical storm cuts off their only escape route, the team must work together to find their way through an uncharted and dangerous underwater labyrinth to make it out alive. With time running out, can they survive, or will they be trapped forever?