Two decades after the end of the Second World War, Anna Marlow stands among a crowd of spectators gathered around a lake in Norway. She is watching an aircraft being raised up from the depths of a lake. As she does so, she remembers its pilot - with a heart that is heavy for reasons far more complicated than a love that was lost during the Second World War. As a British secret agent, Anna had returned to her Nazi-occupied homeland during the war to join the Norwegian resistance. Assuming a new identity, she lived among the Nazis whilst carrying out highly dangerous acts of sabotage, risking her life and the lives of her loved ones.