Captain in the kidnapping unit of the judicial police, Marianne Kacem is in charge of the investigation into the disappearance in Paris of a young student, Lila Rivière. The day before, the two women had met while Lila, at the head of a blog "@lesSiffleurs" aimed at denouncing the street harassment of which she is regularly the victim, had come to file a complaint for assault. While looking for traces of the young Lila, Marianne will confront another generation, but also her own story.