A rich entrepreneur with an irreproachable life is shot dead outside his house with two gunshots. On his body, as a signature, a stone. For the police it's a tough nut to crack, for Crazy Love it's excellent news. Ghezzi and Carella begin their investigations, Monterossi his; while Nadir, a young proletarian looking for revenge, ends up getting into trouble.

Another death, another stone. Ghezzi and Carella are ousted from the investigations and must find a way not to throw in the towel. Meanwhile, two killers accept a job from an unlikely client and Monterossi makes a strange discovery. At odds with his parents, Nadir must ask his friend Francesco for hospitality.

There are three dead. Monterossi's discovery is a thin thread that takes you back in time, to a remote and dark past, into which Ghezzi and Carella begin to dig. Having landed in Reggio Calabria, the two killers try to orient themselves while Nadir plays at being a gangster and ends up in handcuffs.

Is Nadir the stone killer? Ghezzi and Carella find the right trail, a trail that, without knowing it, the two killers are also following. Meanwhile, Monterossi approaches the widow of the third dead man, a refined and cultured woman who fascinates and disturbs him.

Ghezzi and Carella arrest the stone killer, Nadir returns home, as do Socio and Biondo. The case is closed but where is the justice? Monterossi would also like to know, now that he has the fate of another person in his hands...