In the summer of 1968, the year of Prague Spring with a Cold War winter, Oxford students James Borthwick and Eleanor Pike set out to hitchhike across Europe. Having reached southern Germany, they decide on a whim to visit Czechoslovakia, where Alexander Dubcek's "socialism with a human face" is smiling on the world. Meanwhile, in the company of Czech student Lenka Konecková, Sam Wareham --- First Secretary at the British embassy in Prague --- finds a way into the world of Czechoslovak youth; now, nothing seems off-limits behind the Iron Curtain. But the great wheels of politics are grinding in the background. Soviet leader Leonid Brezhnev is making demands of Dubcek, and the Red Army is massing on the borders.

As Allied forces close in on Berlin in spring 1945, a solitary figure emerges from the wreckage that is Germany. It is Marian Sutro, whose existence was last known to her British controllers in autumn 1943 in Paris. Returned to an England she barely knows and a postwar world she doesn’t understand, Marian searches for something on which to ground the rest of her life. When the mysterious Major Fawley, the man who hijacked her wartime mission to Paris, draws her into the ambiguities and uncertainties of the Cold War, she sees a way to make amends for the past and to find the identity that has never been hers.

When 19-year-old Marian Sutro joins the British forces during World War II, her directive is hijacked by another secret organization that wants her to go to Paris to persuade a friend --- a research physicist --- to join the Allied war effort, a mission that could change the course of the war.