On a tranquil summer night in July 2012, a trio of peace activists infiltrated the Y-12 National Security Complex in Oak Ridge, Tennessee. Nicknamed the "Fort Knox of Uranium," Y-12 was reputedly one of the most secure nuclear weapons facilities in the world, a bastion of warhead parts that harbored hundreds of metric tons of highly-enriched uranium—enough to power thousands of nuclear bombs.

The activists—a house painter, a Vietnam veteran, and an eighty-two-year-old Catholic nun—penetrated the complex's exterior with alarming ease; their strongest tools were two pairs of bolt cutters and three hammers. Once inside, the pacifists hung freshly spray-painted protest banners and streaked the complex's white walls with six baby bottles' worth of human blood. Then they waited to be arrested.

With the symbolic break-in, the Plowshares activists had hoped to draw attention to a costly military-industrial complex that stockpiled deadly nukes and drones. But they also triggered a political, legal, and moral firestorm when they defeated a multimillion-dollar security system. What if they had been terrorists with a deadly motive? Why does the United States continue to possess such large amounts of nuclear weaponry in the first place? And above all, are we safe?

In Almighty, Washington Post reporter Dan Zak explores these questions by reexamining America's love-hate relationship with the bomb, from the race to achieve atomic power before the Nazis did to the solemn seventieth anniversary of Hiroshima. At a time of concern about proliferation in such nations as Iran and North Korea, the US arsenal is plagued by its own security problems. This life-or-death quandary is unraveled in Zak's eye-opening account, with a cast that includes the biophysicist who first educated the public on atomic energy, the prophet who predicted the creation of Oak Ridge, the generations of activists propelled into resistance by their faith, and the Washington bureaucrats and diplomats who are trying to keep the world safe.

Part historical adventure, part courtroom drama, part moral thriller, Almighty reshapes the accepted narratives surrounding nuclear weapons and shows that our greatest modern-day threat remains a power we discovered long ago.