Paris, 1899. President Félix Faure has just died in the arms of his mistress, Marguerite Steinheil, also known as ‘Meg’. Between Jules Guérin’s nationalist, anti-Semitic leagues and the threat of anarchy, the French Republic faces an existential threat, so much so that Police Chief Louis Lépine is urgently recalled to office.

Meg has started spying for Puybaraud, the head of La Sûreté, and infiltrates the Guérin family. Meanwhile, Lépine takes stock of the chaos that prevails at police HQ. There is constant friction between his sworn enemy, Puybaraud, and superintendent Cochefert.

Jouin has fallen in love with a young woman, Jeanne, who is a qualified lawyer but cannot practice due to her sex; instead, she is employed by Maître Weidmann in the Jewish quarter of La Villette. She agrees to help the young inspector with the Berger case. In the meantime, Meg entertains Madame Lépine, whose drug habit has come to the attention of Puybaraud…

At La Sûreté, all efforts are being made to solve the Joséphine Berger case – the police need to show they have things under control. In the days leading up to the Dreyfus re-trial, tension is running high in the streets of Paris. Against a background of political instability and personal scandal, Lépine makes a blazing display of his might.

Meg has fallen for an intelligence officer, Gabriel Sabran, but incriminating evidence is piling up against him in the investigation into Joséphine Berger’s murder. This makes Meg a particularly damaging witness for the Guérins and the Comte Sabran de Pontevès.

Sickened by the way the Berger investigation is being run and by Puybaraud, Fiersi has broken with the superintendent. He gives Jouin – who is counting on Jeanne’s help with the case – a crucial bit of information to prove Sabran’s guilt. Having been informed of the imminent roundup at the prefecture, Guérin has barricaded himself on Rue Chabrol.