Well, my guess is it's just about separatin' the wheat from the tares

When a nuclear strike causes an electromagnetic pulse that cuts off all power, water, and communication to the entire western United States, Reese finds herself plunged into an all-too-real fight to survive. As pandemonium grips her city, Reese and her father set out on a desperate journey in search of safety--a perilous trek through a world gone mad where every encounter with a stranger could be your last.