Father and son, managers of a fish market, are at odds with a mafia family because of the gambling debts incurred by their father. Thanks to the carabinieri, the two initially escape an ambush by criminals, but their son will later be found dead. Marshal Rocca will discover that the boy was actually the son of a wealthy entrepreneur and that the man's grandchildren are responsible for his death, eager to grab the entire inheritance.

Marshal Rocca tries to find the culprit of the murder of the parish priest of Santa Brigida, his friend, found killed in the same church. The killing of a journalist shortly afterwards allows the Marshal to discover that the culprit is the one who was posing as a simple witness to the murder of the parish priest.

A waitress, his former lover, is suspected of the murder of Michele Bono, found dead in a hotel. However, the subsequent death of a former police inspector leads Rocca to expose a gambling ring in the hotel. The assassin turns out to be the stepdaughter of Bono, her lover, whom she had killed with the motive of jealousy.

Marco is accused of ill-treatment and rape by an informant. Marshal Rocca is furious with his son-in-law for his daughter's betrayal, but he does not believe that Marco could have been capable of violence. He will later discover that the real culprits are the coach and attorney of a cyclist who fell into a coma due to the use of doping: the two had forced the girl to use Marco to sidetrack the investigation.

Marshal Rocca investigates the murder of an art collector, murdered in his home during a robbery. The stolen paintings, however, were fakes, whose author Rocca discovers to be the gang leader, in cahoots with the wife of the murdered collector and who will also kill the other two thieves and the partner of one of the two.

Rocca is faced with a case that seems to have to do with a satanic ritual. The discovery of a note inside a dead kitten with the inscription "Male returns healed" and, shortly after, the killing of a girl named Marisa, lead the Marshal to suspect a connection with the case of Professor Aleppi, of which he had occupied seven years earlier. In fact, the professor had been the director of an orphanage whose former pupils had founded a sect to avenge their deaths.