When a massive solar flare wiped out all modern technology across the globe, the small town of Abney, Texas, was thrown into chaos. Shelby Sparks and her teenage son, Carter, have found refuge, but Shelby knows she can't simply remain hidden. Carter is a type 1 diabetic in need of insulin-and Shelby will risk her life traveling to Austin to make sure he gets it.

Shelby's best friend and high school sweetheart, Max Berkman, won't even consider letting her make the perilous journey alone. Together, they manage to reach the capital-only to discover that while things are desperate in Abney, Austin has turned into an urban nightmare on the brink of anarchy.

Shelby and Max's search for medical supplies will lead them into terrifying territory, where the only thing more uncertain than finding what they need is the hope of making it out of the city alive.