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. Soon, they are confronted with the unavoidable question: Can they survive, or will they be trapped forever?