In August 2021, writer Lola Lafon spent a night alone in the Annex of the Anne Frank Museum, where the young girl and her family hid from 1942 to 1944. This experience gave rise to a book, Quand tu écouteras cette chanson, and now its documentary adaptation. Over the course of a night, the author revisits her story. An inner journey around the figure of Anne Frank and the power of writing in the face of oblivion.