'This is a book about surprises - at any rate, it has surprised me.' In 1999, Michael Holroyd published Basil Street Blues, in which one of our finest biographers turned his attentions to something more personal - his own family. But rather than the story being over, in fact it was just beginning. For as the letters from readers started to arrive, the author discovered an extraordinary narrative that his own memoir had only touched upon. Mosaic, then, is Michael Holroyd's piecing together of these remarkable stories: some of which are pleasant surprises, other more startling. There is the death of the fearsome headmaster at his school, who was murdered by one of the boys after he left: the discovery that his Swedish grandmother was the mistress of the French anarchist writer Jacques Prevert; and a letter from Margaret Forster about the beauty of his mother, that leads to his remarkable account of a decade-long affair. A love story, a detective story, a book of secrets, Mosaic is both a beautifully written journey into a forest of family trees, and a fascinating insight into the workings of genealogy.