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.