This fascinating work of fiction is based on the true story of the author's grandfather, Immanuel Birnbaum, the protagonist of the novel. Raised in a Jewish family, Immanuel was the son of a very well-known Jewish composer and cantor in the Konigsberg synagogue. Based in Warsaw during the 1930's, he was a journalist and wrote for some of the most important German language newspapers. After 1933 he was no longer allowed to contribute to German newspapers and in 1939, just months before the war broke out, he escaped to Sweden with his wife and two sons.

The novel opens with Immanuel living as a refugee in Stockholm with his family. He continues to contribute articles to a liberal Swiss newspaper in Basel under the name Dr. B. and also begins to work as an editor for the legendary German publisher, S. Fischer Verlag. Gottfried Bermann Fischer established a Fischer office in exile, in Stockholm, to evade German censorship during the war, and published there some of the most celebrated writers in the German language: Thomas Mann, Stefan Zweig, among others. S. Fischer Verlag's books were then distributed in Germany by a sympathetic Dutch publisher.

Immanuel Birnbaum also becomes involved, unwittingly, with British intelligence, a group of Englishmen who produce and distribute anti-Nazi propaganda in Stockholm. On orders from Winston Churchill, the group is soon planning to sabotage Sweden's transport of iron ore to Germany. They plot to blow up the Swedish trading port of Oxelösund and force neutral Sweden into the war. However, the Swedish postal service picks up a letter written in invisible ink, and the plotters are exposed. This letter, often mentioned in military history as a mysterious element in the story, was in fact written by Dr. B. But why on earth would he have wanted to tip off the Germans...