When a remote camera on a large, rugged expanse held by the Land Trust for Wildlife Conservation picks up a blurry image of what could be a mountain caribou, they contact Alex Carter to investigate. After all, mountain caribou went extinct in the contiguous U.S. years ago, and if one has wandered down from Canada, it’s monumental. But when Alex arrives on scene in the Selkirk mountains of northeastern Washington state, she quickly learns that her only challenge isn’t finding an elusive caribou on a massive piece of land. The murdered body of a forest ranger is found strung up in the town’s park, and Alex learns of a backcountry hiker who went missing in the same area the year before.

Fresh off her wolverine study in Montana, wildlife biologist Alex Carter lands a job studying a threatened population of polar bears in the Canadian Arctic. Embedded with a small team of Arctic researchers, she tracks the majestic bears by air, following them over vast, snowy terrain, spending days leaning precariously out of a helicopter with a tranquilizer gun, until she can get down on the ice to examine them up close. But as her study progresses, and she gathers data on the health of individual bears, things start to go awry. Her helicopter pilot quits unexpectedly, equipment goes missing, and a late-night intruder breaks into her lab and steals the samples she’s collected. Someone doesn’t want her to complete her study, but Alex is not easily deterred.

While studying wolverines on a wildlife sanctuary in Montana, biologist Alex Carter is run off the road and threatened by locals determined to force her off the land. Undeterred in her mission to help save this threatened species, Alex tracks wolverines on foot and by cameras positioned in remote regions of the preserve. But when she reviews the photos, she discovers disturbing images of a severely injured man seemingly lost and wandering in the wilds. Then another invasive predator trespasses onto the preserve. The hunter turns out to be another human --- and the prey is the wildlife biologist herself. Alex realizes too late that she has stumbled onto a far-reaching illegal operation and now has become the biggest threat.