Letter from an Unknown Woman is a 1948 American drama romance film directed by Max Ophüls. It was based on the novella of the same name by Stefan Zweig. The film stars Joan Fontaine, Louis Jourdan, Mady Christians, and Marcel Journet.
In 1992, Letter from an Unknown Woman was selected for preservation in the United States National Film Registry by the Library of Congress as being "culturally, historically, or aesthetically significant".
In Vienna in the early twentieth century, Lisa (Joan Fontaine), a teenager living in an apartment building, becomes fascinated by a new tenant, concert pianist Stefan Brand (Louis Jourdan). Stefan is making a name for himself through energetic performances. Lisa becomes obsessed with Stefan, staying up late to listen to him play, and sneaking into his apartment and admiring him from a distance. Despite her actions, they only meet once and Stefan takes little notice of her.