The city of Aix-en-Provence is under a very particular tension. The trial of Mathias Rousseau, the man who called himself the "Zodiac", will begin. Called back to France to testify, Esther Delaître moved with Quentin, the child she adopted, to her brother Jérôme, in her house on the shores of Lake Geneva in Switzerland. But the disappearance of little Lucie Daguerre calls everything into question. The family of the missing child runs the Institut Daguerre, a renowned school where Mathias stayed for a few months when he was younger. Does the "Zodiac" pull the strings from its cell? Is he the victim of an imitator?