The deputy commissioner Vanina Guarrasi investigates with her trusted team the suspicious discovery of some pills in the tubs of a famous ice cream parlor, an unusual and curious fact that turns out to be the premise of a much more complex crime. Even Vanina's private life resembles a puzzle: on the one hand there is Manfredi, the romantic doctor who tries to break into her heart. On the other hand, the anti-mafia magistrate Paolo Malfitano, the great love of her life, which she seems to want to leave behind.

The black sand of Etna submerges Catania and Vanina is forced to come to terms with the end of her story with Paolo, while a corpse re-emerged from the past claims her attention. In an uninhabited villa the mummified corpse of a woman is found: it is Maria Cutò, a prostitute who died fifty years earlier. Vanina discovers that Gaetano had also been killed there, the man with whom she was supposed to flee, perhaps killed by the mafia. But what is the truth? Is it pure coincidence? The case at the time had been solved quickly but the policewoman discovers a terrible past.

A new case reunites the paths of Vanina and Manfredi. It was the doctor, in fact, who saw two suspicious men as they threw a heavy suitcase into the sea, soaked in blood, so Vanina will find herself investigating the murder of a girl that took place in a villa. The victim is the lawyer Lorenza Iannino of whom no other traces can be found. The villa turns out to be owned by the lawyer Elvio Ussaro, a murky prince of the bar, but a macabre discovery will overturn the course of the investigation. Meanwhile, just when Vanina opens her heart to Manfredi, a family commitment puts her face to face again with Paolo and with the unresolved of their relationship.

Vanina investigates the death of a man, murdered in the airport parking lot. The victim, a sixty-year-old Cuban with American and Italian citizenship, was an entrepreneur residing in Switzerland. Vanina discovers that he was a prominent member of the American mafia.