Mathilde is a high school French teacher who loves her profession, adores Flaubert and is in love with Etienne. When he leaves her shortly before they get married, her world collapses. Then her sister Agatha, who lives with Frédéric and their daughter Lili, welcomes her into her home. There follows a period during which the relationship between the sisters develops in an unpredictable direction. Living together in this close family circle is becoming more and more painful. And in the once happy Mathilde, depressed and deeply unhappy, the chilling features of a new personality are revealed. It takes little for a catastrophe to occur.
In Two Sisters, Foenkinos again shows his penchant for the mysterious. The dark tone of the novel, the growing tension are the typical features of the first-class psychological thriller, which is both disturbing and fascinating.