Though the South Pacific's Esa-ala Caves are some of the least-accessible on Earth, expert diver Frank McGuire has explored them for months. On one such expedition, Frank is joined by his teenage son, Josh, and financier Carl Hurley . When a flash flood cuts off their exit, they are caught in a life-or-death situation. With supplies dwindling, the divers must navigate a treacherous labyrinth to find a new escape route or die in the process.
