In his magnificent new novel, Charles McCarry returns to the world of his legendary character, Paul Christopher, the crack intelligence agent who is as skilled at choosing a fine wine as he is at tradecraft, at once elegant and dangerous, sophisticated and rough-and-ready. As the novel begins, Paul Christopher, now an aging but remarkably fit 70ish, is dining at home with his cousin Horace, also an ex-agent. Dinner is delicious and uneventful. A day...