Inspector Petra Delicato, a fascinating and contradictory woman, is called to investigate a series of rapes in the alleys of Genoa. All the assaults have a common denominator: a mysterious mark that the rapist carves on the girls' wrists. Forced to collaborate with Deputy Inspector Antonio Monte, Petra must embark on a dangerous manhunt that will prove more challenging than she could have ever imagined.

The discovery of an unidentified body introduces Petra and Antonio to the world of the illegal guard dog trade. A handsome veterinarian, a trainer, and a mutt nicknamed Spavento will be their companions during a complicated investigation, fraught with murders and twists. To solve a case where nothing is as it seems, Petra and Antonio will be forced to risk everything.

After appearing on a television program, Petra receives a package at the police station. Inside, preserved in a jar of formalin, is a surgically severed penis and a clue to decipher. Is it a threat or a dramatic cry for help? In the following days, more packages and new clues arrive. Petra and Antonio must enlist the help of Egor, a charming policeman recently arrived from Moscow, to solve a nightmarish puzzle.

When the police chiefs are engaged in a classified investigation, the death of a hated gossip columnist is a problem best left to the lowest of the queue: Petra and Antonio. But as they delve into the underworld of entertainment, our heroes discover that their case may be the most sensitive yet. Trying to piece together an uncomfortable truth, Petra and Antonio must follow the investigation to Rome, where Petra will be forced to confront Nicola, her first ex-husband.