Nine months have passed since the last investigation and in this time frame many balances have changed at Sant' Andrea. Deputy Commissioner Tiziana Torre has been transferred and Giorgio Pettenella, who has just been promoted, has returned to take her place. There is a familiar atmosphere and the police station seems to have finally regained its former harmony.

During the dress rehearsal of a Neapolitan skit, a stage gun actually fires. The protagonist collapses lifeless on the ground and never gets up again. It is immediately clear that someone has replaced the fake gun with a real, loaded one. The investigation at the Sant'Andrea police station unfolds in an environment full of poison, intrigue and ambition.

At a bus stop a thief tries to snatch a purse from an elderly woman. Most of the bystanders pretend nothing is happening while a man, shocked by what is happening, confronts the criminal. With the assault report and the identikit obtained thanks to his testimony it will not be difficult for the men of Sant'Andrea to identify the thief.

In the living room of a villa lie the bodies of three women with their throats cut: a mother, a daughter, and a neighbor. On the landing of the upper floor a man is fighting for his life, also in a pool of blood. No sign of forced entry and nothing to suggest an attempted theft.

A well-known lawyer is robbed by a woman in a balaclava. A man catches a young boy in his apartment, and the same man is robbed a few hours later while walking down the street. The men on the team work to find a common denominator for all these crimes.

The lifeless body of a psychologist, a well-known university professor, is found in a peripheral area of ​​the city. Digging into his private life reveals a homosexual relationship with a young researcher. The boy, an old acquaintance of Simone, appears very willing to collaborate. The young man claims to have an alibi but this is not very reliable, therefore he is accused of the murder.

A jeweler is robbed by two boys disguised as workers, impossible to trace their identities: the man was unable to see their faces. An interesting detail emerges from the surveillance cameras: one of the two robbers was wearing a cap with the logo of a yacht club. Ramaglia goes to the nautical club and discovers that among the young people of the reformatory who make clothing for the yacht club there are three old acquaintances of Sant'Andrea.

The body of a girl is found in the waters of a canal. No documents, no signs that could lead to her identity. A young man, recognizing the photo in the newspaper, reveals to the men of the investigation that he had met the victim the day before. She was an Argentine journalist who intended to write an important investigation by collecting numerous testimonies.

The men of Sant'Andrea are dealing with a raid inside a nightclub. After intercepting some drug dealings and guarding the entrances to the club, the policemen move on to searches. Among the many young people stopped and taken to the police station, there is a student who reacts desperately: a small bag of cocaine was found in her bag and she declares that she does not know who could have put it.

A fire breaks out in an illegal parking lot, among the cars on fire is that of the manager of a private company that manages the water supply. The Sant'Andrea agents discover from the bank records that the woman regularly pays protection money and near the manager's office the body of a worker is found.

Following the failure of an important operation, Cafasso is convinced that the mole hidden in the Bellini police station is Commissioner Livia Palma. In fact, a call was made from her phone to a mysterious cell phone, registered to a dead man. A number activated immediately after the escape of the boss Vincenzo Matrone.

Antonio and Demetrio question the colleagues of a worker who fell from a scaffolding at the port and who is now hospitalized in serious conditions. No one knows why the worker was up there and there appear to be no witnesses to the accident. The investigators suspect an attempted suicide to collect the insurance, the doctors find a wound to the man's head caused by a metal edge.

Mafia boss Vincenzo Matrone has escaped from the rehabilitation clinic where he was hospitalized. A young policeman, the only guard on duty for the boss at the time of his disappearance, becomes the scapegoat because he had left the room for a few minutes in order to help a nurse dealing with a woman in a coma.

The men of Sant'Andrea and those of the Bellini police station, led by Cafasso, continue to investigate the deaths of Nigerian prostitutes, their pimps and their customer base. The prime suspect in the murders, however, is found dead in his home. Dr. Mari's autopsy quickly reveals that the alleged serial killer did not commit suicide but was murdered.

While Cafasso and the men of the Bellini police station are still at sea with the investigation into the murder of a black prostitute, a new crime similar to the first unexpectedly occurs. This time the agents of the Sant' Andrea are dealing with it: a Nigerian prostitute, killed with two shots to the heart, lies motionless in the arms of a boy who does not want to separate from her.

The investigations continue to capture the boss Annibale Ruotolo. After discovering that the ambush set on Ruotolo two years earlier was organized by Vincenzo Matrone, an old acquaintance of Sant' Andrea, the new vice-questor Tiziana Torre and the commissioner Pettenella ask the magistrate for authorization to meet the young Camorrista in prison.

A young boy, who Antonio helped in the past to get out of the drug scene and who joined an association for the recovery of young people at risk, goes to the police station to ask for help: his stepfather, a criminal with violent behavior, has been released from prison thanks to a pardon and now represents a threat to him.

Having entered the lair of the boss Annibale Ruotolo, the police find that the apartment is empty and there is no trace of the Camorrista. Did the boss understand what their plan was or is there a mole who has spilled the beans? Someone made Anna disappear, who recently pretended to be a corrupt policewoman to allow our men to capture Ruotolo.

A man lies lifeless on the ground with scissors stuck in his throat, a possible macabre signal sent by the Camorra to indicate that he had talked too much and therefore deserved that tragic end. Walter, arriving at the scene of the murder, recognizes his informant: the tailor Ilario Bigi.

After the discovery of the body of a man of Chinese origin, Dr. Veneziani begins the investigation at the crime scene. Pettenella, Walter and Pietro think of a possible war between the Camorra and the Chinese mafia. All possible investigative leads must be pursued and Anna tries to investigate what is happening within the Chinese community.

A man is suddenly killed on the platform of a train station just before the arrival of the train he was waiting for. Dr. Veneziani, who rushed to the scene of the murder together with Sciacca and De Luca, finds a briefcase containing a gun.

A boy who arrived in Naples from South America is taken to the emergency room for a serious illness. Sciacca and Silla, who rushed to the hospital, learn that the young man had cocaine pellets in his stomach and that, surprisingly, he asked to file a complaint.

A blood-stained bedroom, the lifeless bodies of a man and a woman, a new complicated case for the agents of the Sant' Andrea police station. At the crime scene there is no sign of violation, but the killer left his traces on a protruding screw.

An elderly man arrives at the police station to report the discovery of a fanny pack containing a lot of money and a notebook with indecipherable notes. Alfio and Antonio discover that the man is an internationally renowned university professor and immediately speak to Cafasso. What is the relationship between an apparently honest professor and the Camorra?

The day after the violent explosion at Sant'Andrea, the policemen share a deep sorrow and the angry desire to capture the person responsible. The question arises about the true identity of the accountant who died in the terrible ambush together with the group of criminals who infiltrated to free him, what facts did he know?

The body of a girl from Naples' upper class is found on a beach in the city. Only one clue: on the victim's cell phone, a message from her boyfriend who arranged to meet her in that place. When questioned by Pietro, the boy says he knows nothing about the message, that he has lost his cell phone and that he has an alibi: at the time of the murder, he was at a soccer game with friends.