Celestria always spends her summer holiday at Pendrift Hall, the rambling, shabby Cornish mansion adorned with wisteria and clematis that has been home to the Montague family for generations. In the summer of 1958, the highlight is a lavish ball in honour of Archie Montague's fiftieth birthday, and the beautiful girl, on the cusp of womanhood, is looking forward to practising her flirtation skills on the Wilmotte boys. But what is supposed to be a night of celebration ends in catastrophe. As a result, Celestria's grandfather encourages her to play detective, to seek out an explanation for the bewildering events. The quest takes her to the heel of Italy, to the rugged beauty of Puglia and the cool cloisters of the Convento di Santa Maria del Mare.