A FINALIST FOR THE LA TIMES BOOK PRIZEA NEW YORKER BEST BOOK OF 2025'The best book I’ve read in the past year . . . A masterpiece' Financial Times‘A voyage into the heart of twentieth-century darkness [...] narrated with the twists and turns of a detective story’ ObserverJoe Dunthorne never met his great-grandfather Siegfried: an eccentric Jewish scientist who escaped Nazi Berlin in the 1930s and snuck back under cover of night to rescue the family heirlooms. Decades later, Siegfried wrote about his adventures in a memoir so long and rambling that almost no one ever managed to read it. Decades after that, his great-grandson Joe unearthed the dusty manuscript and got a nasty surprise. Because hidden on page 1,692 of the unreadable memoir was a shocking confession... So begins a gripping journey into the twisting moral maze of the twentieth century – a journey to uncover a radioactive family secret.