A supervolcanic eruption in Yellowstone Park destroys crops and livestock, clogs machinery, and makes cities uninhabitable. Those who survive find themselves caught in an apocalyptic catastrophe in which humanity has no choice but to rise from the ashes and recreate the world.

Ren is a park ranger, tasked with duties both mundane and thrilling: breaking up fights at campgrounds, saving tourists from moose attacks, and attempting to broker an uneasy peace between the wealthy vacationers who tromp around with cameras and the locals who want to carve out a meaningful living amid this western landscape. When Ren discovers his friend Hilly, a biologist and wolf expert, nearly dead in the steel jaws of a wolf trap, he hopes it's...