Die Unbekannte (The Unknown) was adapted by director Frank Wysbar from his own novel (co-written by R. C. Muschler). Sybille Schmitz, who was previously so memorable as the attractive bloodsucker in Dreyer's Vampyr, heads the cast as woman-of-mystery Madeleine. The story begins at the ending, as Madeleine's dead body is pulled from the river. With no identification on her, Madeleine remains unidentified -- to everyone but the viewer, who is apprised of the girl's melancholy history via flashback.