In the winter of 1885, decorated war hero Colonel Allen Forrester leads an exploratory expedition up the Wolverine River and into the vast, untamed Alaska Territory. Leaving behind Sophie, his newly pregnant wife, Forrester records his extraordinary experiences in hopes that his journal will reach her if he doesn't return. As they map the territory and gather information on native tribes, whose understanding of the natural world is unlike anything they have ever encountered, Forrester and his team can't escape the sense that some great, mysterious force threatens their lives. Meanwhile, in Vancouver, Sophie chafes under the social restrictions of a pregnant woman on her own, and yearns to travel alongside her husband. She, too, explores nature, through the new art of photography, unaware that the coming winter will test her own courage and faith to the breaking point.