The Great Smog. London. 1952. A dense, choking fog engulfs the city and beneath it, history is re-written... Spring 1940. The world is on the brink of the biggest war ever known. At a meeting at Downing Street, Britain's leaders decide who is to succeed the exhausted appeaser Chamberlain. But when Churchill is persuaded to serve under Halifax, history as we know it is turned on its head. Winter 1952. Though war rages on in the east, Britain is at peace with Nazi Germany and many now see the country as little more than a corrupt German satellite state. The free press has been suspended, the streets are patrolled by violent auxiliary police, the British Jews face ever tighter constraints and there are dark, terrible rumours about what is happening in the basement of Senate House - held by the German Gestapo. Meanwhile Civil Servant David Fitzgerald, recruited as a spy by Churchill's outlawed organisation Free Britain, must complete a mission of desperate importance. His old friend Frank Muncaster may have obtained top-secret information with striking ramifications. But David is not the only one looking for Frank, and soon the pair - along with their Free Britain allies, and David's terrified wife Sarah - will find themselves fugitives in their own country, fleeing not just for their lives, but for the very future itself.