In 1962, the United States and Britain unexpectedly clashed over the cancellation of an American missile program, Skybolt. Puzzled about how such close allies could fall so afoul of each other, President Kennedy asked a professor he admired, Neustadt, to study the matter -- opening doors and files to him in Washington and even helping him in London. After reading Neustadt's vivid report in November 1963, Kennedy gave it to his wife, remarking, "If you want to know what my life is like, read this." Then they left for Dallas, and Neustadt's report was locked away for 30 years. Now declassified, it offers a marvelous introduction to the personalities and the arcane issues involved, supplemented by Neustadt's new research in the now-opened British archives. His report is both a microstudy of the details that animate real issues in government and a masterpiece of writing. It looks deeply not only into international policymaking but into the heart of relations among allies. It also offers a very timely lesson: the United States ought to favor its friends with the kind of attention it usually accords only to its enemies.