Yellowstone National Park sits on a hotspot: a plume of molten rock coming up from deep inside the earth capable of volcanic eruptions far greater than any that have occurred in times past. It has been silent for many years, providing false security for a nation unprepared for the full force and fury of nature unleashed.

It begins with explosions that send lava and mud flowing far beyond Yellowstone towards populated areas. Clouds of ash drift across the country, nearly blanketing the land from coast to coast. The fallout destroys crops and livestock, clogs machinery, and makes cities uninhabitable. Those who survive find themselves facing the dawn of a new ice age as temperatures plummet worldwide.

Colin Ferguson is a police lieutenant in a suburb of Los Angeles, where snow is falling for the first time in decades. He fears for his family who are spread across America, refugees caught in an apocalyptic catastrophe where humanity has no choice but to rise from the ashes and recreate the world…

Harry Turtledove, the New York Times bestselling author of numerous novels, has a PhD in Byzantine history. Nominated for the Nebula Award, he has won the Hugo, Sidewise, and John Esthen Cook Awards.