HQ has ruled that Chief Inspector Aliette Nouvelle's failure to carry her gun directly contributed to the messy conclusion of a major murder case she'd led the previous summer. Her career now depends on a drastic about-face. Aliette has been ordered to come into the city to practice at the Beziers police shooting range and attend counselling sessions two nights a week with psychologist Gabrielle Gravel. For Aliette, this is not only humiliating, it's inconvenient. Beziers is a 40-kilometre drive from her home base in Saint-Brin, a sleepy wine town in the south of France. But she will required to attend until she can prove she is prepared to use deadly force in the execution of her duties.

Meanwhile, a killing spree is taking place in Beziers. After the first savage knifing of a homeless young man, a deranged street person is suspected. But the working theory changes when victim number three turns out to be PJ Inspector Pierre Tropéano. A knife is left in his gut, and his gun is gone. It will be used to kill the next victim, another homeless young person.

As she navigates Beziers' night streets, trying to come to terms with the SIG Sauer SP2022 in her holster and how it affects her core identity, Inspector Nouvelle finds clues to the whereabouts of Tropéano's gun — and a killer. Aliette's unofficial, off-duty investigation is motivated by a need to defend her beleaguered colleague, Chief Inspector Nabi Zidane, head of the city-based Police Judiciare force. But the killings in the city are not her business. One false step and she could lose her job. Or her life. Is she ready to use her gun?