An epistolary novel is the name given to a novel or story that is presented as a series of letters. Address Unknown is an epistolary story, formed from a correspondence between two German men named Martin and Max. The correspondence begins at the moment of their departure, when Martin leaves the United States to return to Germany. This is a moment of divergence for their friendship, and, through the epistolary format, the audience is able to grasp the depth of friendship and when it shifts.

The letters contain references to events and circumstances that both men understand but do not need to explain in detail. For example, Max mentions his sister in his first letter, alluding to a potential relationship between Martin and Griselle as being like “quick storms.” The letter does not need to provide specifics; both the writer and the intended reader are keenly aware of what happened, so the events are relegated to subtext by the story’s format.

The unspoken nature of events and characters add a sense of reality to the friendship. Max and Martin are conducting a private conversation; that they have been such good friends for so long means that they can leave so much unsaid.