Harry Baldwin and his family—wife Ann, teenage son Rick, and daughter Karen—set out on a camping trip early one morning, planning to escape the hustle of Los Angeles for a peaceful vacation. Just as they leave the city, a series of bright flashes and distant rumbling cause them to turn on the car radio, only to hear that Los Angeles has been decimated by a nuclear attack. Shocked and frightened, Harry decides to continue on to their camping destination, believing it to be safer away from the chaos. During the journey, they witness looting, violence, and panic spreading among the population as society begins to break down in the wake of the disaster.

As the family reaches relative safety in an isolated area, they struggle with morality and the lengths to which they must go to survive. Harry grapples with tough decisions about how to protect his family from not only fallout and radiation but also from desperate and dangerous people they encounter along the way. Tensions rise as resources dwindle and human nature rears its brutal head. Throughout their ordeal, each family member must confront their fears and ethical dilemmas, testing their resolve to survive in a world forever changed.