Alister Grierson directs this James Cameron-produced, subterranean action adventure about a group of divers whose expedition turns into a fight for survival. While exploring the world's largest and most remote cave system in the South Pacific, a sudden storm forces veteran diver Frank McGuire (Richard Roxburgh) and the rest of his team, including teenage son Josh (Rhys Wakefield), to go deeper into the caves. With waters rising and resources running out, Frank and his team pin their hopes on finding a previously unknown exit. But on discovering the way ahead is blocked, the group are soon forced to negotiate a perilous route through an underwater maze, as they desperately try to find their way back to the surface.