Synopsis: Follows a team of underwater cave divers on a treacherous expedition to the largest, most beautiful and least accessible cave system on Earth. Master diver Frank McGuire (Richard Roxburgh) has explored the South Pacific's Esa-ala Caves for months. But when his exit is cut off in a flash flood, Frank's team—including 17-year-old son Josh (Rhys Wakefield) and financier Carl Hurley (Ioan Gruffudd)—are forced to radically alter plans. With dwindling supplies, the crew must navigate an underwater labyrinth to make it out.