On 11 March 1958, in Mars Bluff, South Carolina, a man called Walter Gregg was building shelves in his shed with his son, when a Mark 6 atom bomb landed in his yard. Mrs Gregg was inside [the house], sewing. The little Gregg girls were playing outside. The fissile core of the bomb had been removed for safer transit, but the explosives that powered it nonetheless blew the Gregg house to bits, killing half a dozen of the Gregg chickens. In military talk this sort of thing is known as a broken arrow", an accident involving nuclear weapons that falls short of causing risk of war, and Schlosser's book is about the several dozens of these that have happened - counting only those of US origin - since the atomic bomb was invented in 1945. The next-up sort of accident is called a Nucflash. So far, it hasn't happened, but Schlosser considers this due as much to luck as anything else. [The book] aims to "pierce a false sense of comfort", ... the popular assumption that ... the threat of nuclear escalation has gone away for good. It hasn't, is Schlosser's miserable message. "They are out there, soulless and mechanical, sustained by our denial - and they work." In this book, he's interested in how "the effort to control nuclear weapons - to ensure that one doesn't go off by accident" is undermined, over and over again, by demands from the military for bombs they can trust to explode.