A woman is beaten to death in a seemingly peaceful neighbourhood. Myrtille Masquelier lived on the margins of society: alcoholic, unemployed, she lived alone, her daughter having been taken into care. When her husband's body is found in the cellar, questions are asked.

Olivier Chabert kills his wife and children despite the intervention of the Criminal Brigade at the last minute. When the madman manages to hang himself while in police custody, Rovère feels all the more responsible as it takes him back to a painful past. Chabert was over-indebted to a small credit organization, whose director, Gérard Falsetta, was then found burned in his car. Suspicion fell on Nathalie Forest, the woman who threatened Falsetta. And for good reason: two years earlier, her husband had killed himself with their little daughter.

The body of José Lorquin is discovered, horribly mutilated. The victim lived in the François-Villon city, a quiet place where everyone passes each other without knowing each other. However, everyone on Staircase C knew him. Very helpful, he was always ready to lend a hand or lend money. The fact that he had money and showed it could have made people jealous in this world with difficult incomes. For the caretaker of the building, he would have fallen into a trap set by his neighbors, and little Anaïs would have served as bait.

Anatole Bara, 80 years old, lies on the floor of his kitchen, his skull shattered. The shopping bag is still full of groceries, his wallet is empty. Commander Rovère does not believe it was a heinous crime, because the killer took the trouble to put clean clothes on his victim and took the time to dine next to the corpse. When others are killed, Judge Lintz calls on Nathan Benesti, her former professor at the National School of the Judiciary and criminal expert. But between Rovère and the criminologist, the tension is palpable.

Jean-Philippe Tardieu, a psychiatrist also working as an expert in the courts, is found dead in the underground parking lot of his office. Rovère is in charge of the investigation. But he does not have time to involve judge Nadia Linz about this case, she has just disappeared under mysterious circumstances. In reality Nadia has been kidnapped and is being held captive in a suburban house by the relatives of a former accused. Richard Pessoa, whom Judge Linz had indicted a few years ago, has just committed suicide in his cell and his family has decided to organize a mock trial behind closed doors. They accuse the judge of not having investigated the case impartially and not recognising that Richard had been declared insane at the time of the facts. A race against time begins to find the judge...