On May 16, 1937, in Paris, at the end of the day, Laetitia Toureaux, a beautiful young woman of 29 years old, rides in the metro at Porte de Charenton station, head of line 8. She takes place, alone, aboard the first class wagon. Less than three minutes later, the travelers who go up to the next station discover his stabbed corpse. Passionate crime or political execution?

On August 21, 1933, Violette Nozière, 18, poisoned her parents with sleeping pills, before going out to dance. When she returns, she makes sure they are inanimate before opening the gas to make it look like a suicide, then calls for help. Her father did die, but her mother survived. After the survivor's testimony, Violette, already suspicious in the eyes of the investigators, is arrested. The young woman accuses her father of having abused her, but it is the financial motive that justice retains. The case will fascinate public opinion and intellectuals of the time.

On March 11, 1944, the nauseating smoke that escaped from the chimney of the mansion at 21 rue Le Sueur, in Paris, led the neighbors to alert the police. The owner, a certain Doctor Petiot, is absent. The firefighters break a window to enter. In the cellar, near the boiler which is running at full speed, they discover human remains. It quickly turns out that Doctor Petiot murdered those he claimed to want to help leave occupied France.

Twenty years before Jack the Ripper rages in Britain, Paris is experiencing a wave of murders of prostitutes particularly violent. From 1861 to 1866, nine girls of joy, as well as the child of one of them, were slaughtered by an individual whom the police could not apprehend. Many witnesses describe him as a disturbing-looking worker, with a somber gaze and a tattoo on his arm, who proclaims "Born under a bad star". This sad character persists on his victims, strikes them with numerous stabs, with such violence that he sometimes fails to decapitate them. He was finally arrested on January 11, 1866, after an attempted murder of a painter. His name is Louis-Joseph Philippe and has all the characteristics of the psychopath.

Jeanne Weber, nurse and prostitute, was accused of having murdered, between 1905 and 1908, a dozen children, including two of hers. Nicknamed "the ogress of the Golden Drop" because of the name of the street where she lived, she was first acquitted during her trial in 1906. Experts and doctors, divided on the circumstances of the death of her supposed victims, had then concluded to natural deaths. But two years later, caught in the act of murdering a 10-year-old child, she was recognized as an authentic serial killer. She was then declared mad and imprisoned at the asylum in Maréville, where she hanged herself in 1910.