Oh Pure and Radiant Heart imagines a world in which the three geniuses who were key to the invention of the atom bomb - physicists J. Robert Oppenheimer, Enrico Fermi, and Leo Szilard - are displaced to contemporary America at the moment history's first mushroom cloud rises over the New Mexico desert on July 16, 1945.<BR>When Oppenheimer, Fermi, and Szilard appear in Santa Fe in 2003, Ann, a reference librarian, and her doting gardener husband, Ben, take them in. With the long-dead scientists for houseguests, Ann and Ben are swept up in a quixotic and calamitous quest that takes them from Ground Zero in Hiroshima to the Nevada Test Site to the United Nations on a ramshackle pilgrimage for nuclear disarmament. As the scientists, faced with the evidence of their nuclear legacy, cross the United States - bankrolled by an earnest, pot-smoking Tokyo millionaire - they attract a growing convoy of RVs carrying groupies, drifters, activists, former Deadheads, New Age freeloaders, and religious fanatics who believe Oppenheimer is the Second Coming. Meanwhile Ann and Ben fight to save their marriage, gravely threatened by her obsessive devotion to the ghostly men of the Manhattan Project.