On 15th April 1936 the 3rd Reich's Ambassador to Britain died in post. Fluent German-speaking Fleet Street journalist Sebastian Ferrers knew the late Ambassador socially. He also enjoys a close friendship with Sonya Hayek, an attaché at the Embassy. Sonya is fearful that, despite her seniority, her Jewish antecedents place her in jeopardy of being recalled to Berlin.

Rumour in Whitehall has it that the next German Ambassador could be 38 year-old Dr. Joseph Goebbels. Ferrers is asked by the British Foreign Office to 'weight' his articles positively toward the Third Reich, to curry favour with Goebbels and gain access to him during the forthcoming Berlin Olympics. Meanwhile, Ferrers and Sonya become more emotionally involved spending their first night together at Midhurst following a diplomatic polo tournament at Cowdray Park. But they are also aware that Sonya is under surveillance from the Embassy's SS.

Ferrers is kept busy writing on international affairs and observing British Union of Fascists rallies. He uses his connections to visit the exiled Emperor Haile Selassie of Ethiopia in Worthing and meets Viscount Astor and others in the Naval Port of Plymouth. This includes the local Jewish MP Leslie Hore-Belisha. Anti-Semitism and Mosley-led Blackshirt fascism is rife in Britain.

Ferrers attends the Olympic Games in Berlin and, as a perceived Friend of the Reich, meets Goebbels, Goering and Von Ribbentrop. He is present when Von Ribbentrop is named by Hitler in person as the next Ambassador to London. Ferrers wins the Correspondents' Olympic Raffle Prize of a return flight to the USA on board the Zeppelin Airship Hindenburg. He guesses that the result was fixed, but uses the visit to join Sonya and her emigrant Austro-German parents in New Hampshire. Sonya is strangely distant and uncertain about returning to London. Back in England, Ferrers lunches with Churchill at Chartwell and with the Von Ribbentrops in Belgravia, where he is seated beside architect Albert Speer.

Meanwhile, Ferrers is recruited discreetly by Antonia Montagu into the British Secret Intelligence Service under the control of Eros. He is assigned a mission by the SIS to return to Berlin and to participate in a covert operation at Sachsenhausen Concentration Camp, to either free or execute a fellow British Agent held within. To his horror, the Agent turns out to be Sonya, now interned as a Jew but, as yet, undetected as an SIS informant.

Fortunately the rescue is achieved and Sonya is taken to a safe house. During Christmas week she is able to ride with Ferrers in London's Hyde Park, under close security escort. They speak of marriage, but an SS assassin steps in front of them and shoots Sonya. Is it fatal? Alone in London on Christmas Day, Ferrers is surprised to find that his neighbour in Dolphin Square is Antonia Montagu. She reveals herself to be "Eros" and introduces her intriguing temporary flatmate.