Joe Dunthorne tells us he originally envisaged this book as a story of his grandmother’s childhood escape from the Nazis; the reality turned out to be more complex. Narrated with the twists and turns of a detective story, Children of Radium is a family memoir that records the mazy path by which the prize-winning Welsh novelist discovered just how little he knew of his German Jewish heritage. His journey begins with “a foot-high block of A4”: a 2,000-page unpublished memoir by his great-grandfather, Siegfried, a Jewish scientist who worked at a secret chemical weapons laboratory near Berlin before he and...