This is the story of the queen, the envoy, his wife and her lover. It is also a book about history, sex, aesthetics, modernism, the Portland Vase and how to repair it, what to wear when disguising pregnancy, Goethe, architectural follies along the Grand Tour, Don Juan, Pygmalion, melancholy and, of course, volcanoes. You really can say it’s about these things with impunity, because Sontag never troubles to disguise the essays inserted in her novel as fiction of any sort. The moment she feels like abandoning the hero and the wife in adulterous embrace for a swift analysis of classical painting, the prose reverts to that cerebral rhetoric which drives her theoretical writings. This involves leaping between opulent banqueting halls in eighteenth-century Naples and the austere chambers of Sontag’s mind. It also means laying aside those old cavils about didacticism being incompatible with art.