Trapped in a superstore by a series of escalating disasters, including a monster hailstorm and terrifying chemical weapons spill, brothers Dean and Alex learned how to survive and worked together with twelve other kids to build a refuge from the chaos. But then strangers appeared, destroying their fragile peace, and bringing both fresh disaster and a glimmer of hope.

Knowing that the chemical weapons saturating the air outside will turn him into a bloodthirsty rage monster, Dean decides to stay in the safety of the store with Astrid and some of the younger kids. But their sanctuary has already been breached once. . . .

Meanwhile, Alex, determined to find their parents, heads out into the darkness and devastation with Niko and some others in a recently repaired school bus. If they can get to Denver International Airport, they might be evacuated to safety. But the outside world is even worse than they expected. . . .