Address Unknown is the story of gradual radicalization, where one adopts radical social and political beliefs. The series of letters charts the journey of one man’s radicalization at the hands of fascism and another man’s radicalization due to immense grief.

The radicalization of Martin is the clearest example of this theme. Between March 1933 and August 1933, Martin is hesitant about the new political system being built in his native country. Max asks him for news about “this Adolf Hitler” (9), who he fears is weaponizing antisemitism to gain power. All that Martin sees is the recovering German economy; he believes that antisemitic violence is a small price to pay for the recovery of his country. This is the turning point for Martin. By dehumanizing others, he too loses his humanity. He is gradually swayed to the Nazi cause, to the point where he is soon defending his “Glorious Leader” to a man he once regarded as a friend. Martin is radicalized to believe in the fascist movement, and Max is forced to watch from afar.

The process of radicalization is closely entwined with identity. In his first letter, when both men are still friends and business partners, Max sympathizes with Martin, who has “never become American despite [his] success” (5).