The German Martin Schulse and the American Jew Max Eisenstein run a successful art gallery in the USA. In 1932, Schulse decides to return to Germany with his family. Eisenstein continues to operate their joint gallery in San Francisco. The two men remain in contact and exchange letters about both professional and personal matters. Initially, it seems that their friendship is not suffering from the physical distance. However, Schulse, who initially viewed the political developments in Germany critically, gradually becomes an avowed Nazi. "Address Unknown," first published in 1938, is a book of unsettling relevance. Designed as a correspondence between a German and an American Jew during the months surrounding Hitler's rise to power, this masterpiece depicts the dramatic evolution.