The Anderson family of five is planning a tramping holiday walking the world-famous Milford Track in Fiordland National Park. Parents Bill and Jeanette Anderson and their three teenagers Russell, Judy and Boffin set off with high hopes and full packs. Things go dramatically wrong when the teenagers get separated from their parents. What was meant to be a fun experience soon turns into a battle for survival. The youngsters must face up to their own fears. It is vital that they overcome natural disasters and fend off hostile creatures in a mysterious lost valley. Only then do they stand a chance of getting out alive.