One of the greatest threats to mankind’s existence has become a reality. The Yellowstone Caldera erupts with a force of a thousand nuclear warheads, expelling seven hundred cubic miles of ash and rock all at once into the sky. And it’s not finished… When Marty and her brother, Ben, relocate with their family from Los Angeles to a small town in Nebraska, the transition isn’t easy. Because they are in high school, their mother believes sending them away for a week to camp might help them make friends. Marty reluctantly agrees and they go to the camp in Wyoming. They are there only a couple of days when the eruption happens. At the edge of the kill zone with no communication or evacuation help in sight, Marty and Ben have no choice but to leave if they want to survive. On foot, they begin the long journey that will take them across the ash strewn countryside flooded with desperate survivors and dangerous conditions. With temperatures plummeting and another eruption looming, can they make it to safety in time? If, of course, a safe place even exists.