The Yukon River is home to the longest — and once largest — migration of Chinook salmon on the planet. Close to half a million fish used to enter the mouth of this river every summer, making their way some 3,400 kilometers from the Bering Sea across Alaska and into the Yukon, to spawn in the streams where they'd once hatched. The Little Salmon River Nation depended on these salmon for their livelihood -- they were also an essential part of their culture, of their understanding of the world. But now the salmon are gone, the fish camps are abandoned, and an entire culture with its way of life is in peril.