Giovanna Scalise, a police commissioner, is transferred from Sicily to Rome for security reasons, where she is assigned command of a police precinct. Scalise's transfer isn't easy: the commissioner is forced to hide from her men the fact that she will be testifying at the mega-trial against her husband's murderers.

In the second season, Giovanna begins a new romance with Inspector Walter Manrico, while Carmine Tonnara, Don Vito's son, dies in prison. The Tonnara family, after the Maxi Trial, has been dismantled. The only one still at large is Mafia boss Vito Tonnara, who, blinded by revenge, tries everything he can to eliminate Commissioner Scalise.

The third season opens with a surprising twist: the arrival of the new Commissioner Giulia Corsi at the Tenth Tuscolano District. She must deal with the legacy of her father, a magistrate murdered a few years earlier, and investigate the murder of Angela Rivalta, Inspector Ardenzi's wife.

In this gripping fourth season, Commissioner Giulia Corsi will have to deal with her father's murderers, who will do everything they can to stop the agents of the Tuscolano Tenth in their investigation, hitting the Commissioner where she is most dear.

In this fifth season, a new elite officer, Anna Gori, arrives at Precinct X Tuscolano, where she will team up with Luca Benvenuto. Meanwhile, a Carabinieri captain, Davide Rea, played by Giampaolo Morelli, tries to gain the trust of Commissioner Corsi and investigates the shooting that left Inspector Belli's wife, Germana Mori, injured and in a coma.

The sixth season begins with a change in the precinct leadership: Giulia Corsi moves to Trieste to follow Carabinieri Captain Rea, and her place is taken by Roberto Ardenzi, who is also in his final year at the precinct. Inspector Irene Valli and Inspector Alessandro Berti join the team.

In the seventh season, Roberto Ardenzi leaves the precinct to join the anti-mafia unit, and Commissioner Marcello Fontana takes his place. Inspector Raffaele Marchetti also joins the team. In this series, Commissioner Fontana must deal with an investigation involving the 'Ndrangheta.

In season eight, after the departure of Commissioner Marcello Fontana, who preferred to return to Calabria with his wife and son, Luca Benvenuto takes over the police station. The team is also joined by Inspector Elena Argenti and her brother Marco.

Luca Benvenuto is appointed chief commissioner of the 10th Tuscolano precinct, while Raffaele Marchetti also leaves the series after the first four episodes. Alessandro Berti also leaves the precinct, having left for America at the end of the previous series.

In season ten, the Tuscolano 10th unit is at risk of closure due to staff shortages, and the few remaining units are disheartened. Luca has become deputy commissioner, while Giulia Corsi decides to return to Rome to investigate a group of drug dealers linked to the Palermo underworld, against the wishes of her superiors.

In this eleventh and final season, Vittoria Guerra and Giuseppe Ingargiola are leaving the scene. The new commissioner will be Leonardo Brandi, an old friend of Luca's.