Seth is a teenage deckhand on his father's boat when he and his dog are washed overboard and swept to one of Alaska's small islands where they struggle for months to survive off land and sea, while his desperate father endures his own emotional journey and never gives up hope.

As their Alaskan village's only survivors of sickness brought by white men one winter early in the twentieth century, sisters Millie, aged thirteen, and Maura, ten, make their way south in hopes of finding someone alive.