When teenagers Beth and Sam Bolton are orphaned, their baby sister is taken into a new home and they decide to set sail for a new life in America. On board the steamer to New York, Beth and Sam meet charismatic gambler, Theo, and quick-witted Londoner Jack and the four band together to seek their fortunes. But the foursome fall foul of local gangsters and flee to Canada, as word gets out that gold has been found in the Klondike. They embark on a dangerous and epic journey to reach the Yukon valley.