It is September 1940 – a year into the war – and as German bombs fall on Britain, fears grow of an impending invasion. Enemy fighter planes blacken the sky around the Epping Forest home of Susan Shepherd and her grandfather, Bertie. After losing her parents to influenza as a child, Susan found comfort in raising homing pigeons with Bertie. All her birds are extraordinary to Susan – loyal, intelligent, beautiful – but none more so than Duchess. Duchess shares a special bond with Susan and an unusual curiosity about the human world.