Preparing for the apocalypse is only the beginning in this survivalist thriller by the USA Today–bestselling authors of Stand Your Ground.

Six weeks ago, former US Marine Patrick Larkin purchased shares in a massive, state-of-the-art underground missile silo for his family. It was a decision based on easing his wildest fears of nuclear holocaust. But then reality strikes with devastating suddenness, razing cities in a searing flash across the nation. No one knows who pulled the trigger. No one knows if the last day on Earth will ever end. But Larkin and his family are the lucky ones—or so they think . . .

Holed up in their fortified sanctuary, with a maximum capacity of four hundred people, the bunker is pushed to its limits—and so are the people locked inside. Tensions rise. Panic erupts. Outside, armed marauders surround the bunker—and they want in. Larkin must convince the others that if they want to survive, they must work together . . . and kill without mercy.