Set in Esa’ala, Papua New Guinea, one of the biggest cave systems on the planet, many underwater, the film tells of a group of hardy cave divers headed by Frank (Richard Roxburgh of “The League of Extraordinary Gentlemen” and “Van Helsing”), “the most respected explorer in the world,” his fiercely rebellious, 20-something son Josh (Aussie pretty boy Rhys Wakefield), who wears either an insincere smile or a disapproving scowl, the team’s arrogant, wealthy benefactor Carl (Ioan Gruffudd of those appalling “Fantastic Four” films), his latest, attractive, mountain-climbing girlfriend Victoria (Alice Parkinson), veteran diver Judes (Allison Cratchley), team manager Crazy George (Dan Wyllie) and others.