Imagine a blackout lasting not days, but weeks or months. Tens of millions of people over several states are affected. For those without access to a generator, there is no running water, no sewage, no refrigeration or light. Food and medical supplies are dwindling. Devices we rely on have gone dark. Banks no longer function, looting is widespread, and law and order are being tested as never before. It isn't just a scenario. A well-designed attack on just one of the nation's three electric power grids could cripple much of our infrastructure -- and in the age of cyberwarfare, a laptop has become the only necessary weapon. Several nations hostile to the United States could launch such an assault at any time. In fact, as a former chief scientist of the NSA reveals, China and Russia have already penetrated the grid. And a cybersecurity advisor to President Obama believes that independent actors -- from "hacktivists" to terrorists -- have the capability as well. It's not a question of if, it's a question of when. And yet, as Koppel makes clear, the federal government, while well prepared for natural disasters, has no plan for the aftermath of an attack on the power grid. In the absence of a government plan, some individuals and communities have taken matters into their own hands. But how, Koppel asks, will ordinary civilians survive?