On a freezing January morning in 1961, eight-year-old Anna's mother disappears into the fog. That same morning, a spy case breaks in the news. Obsessed by stories of espionage, Anna's brother Peter begins to construct a theory that their mother, a refugee from eastern Germany, was an undercover spy and might even still be alive. 'Many writers, from Harper Lee to Suzanne Berne, have explored children's skewed view of the adult world. Georgina Harding has equalled their take ... Elegant ... Lucid, seamless'