A massive solar storm kills billions and wipes out the technological infrastructure, and the few survivors learn that some among them have...changed. It's six weeks after the shock. The smoke on the horizon has diminished, and Rachel Wheeler and her two traveling companions head toward the mountains where Rachel's grandfather Franklin has built a survivalist compound. However, the strange mutated people known as Zapheads seem to be changing from bloodthirsty killers into a force far more menacing. A secret military installation holds the key to rebuilding civilization, but Franklin doesn't trust their intentions. And the Zapheads are adapting to the new world faster than the human survivors, who must fight for their place in a future that may have no room for them.