In the summer of 1962, U.S. defense officials detonated a hydrogen bomb buried deep beneath the desert of Frenchman Flat, Nevada. The blast was so robust that the land around it rose by some three hundred feet and burst open like a very bad boil, leaving a crater eight hundred feet across. Blast debris went everywhere. “By four in the afternoon,” the historian Peter Goodchild has written, “the radioactive dust cloud was so thick in Ely, Nevada, two hundred miles from Ground Zero, that the street lights had to be turned on.” Visible fallout drifted down on six western states and two Canadian provinces—though no one officially acknowledged the fiasco and no public warnings were issued advising people not to touch fresh ash or let their children roll around in it. Indeed, all details of the incident remained secret for two decades until a curious journalist filed suit under the Freedom of Information Act to find out what had happened that day.