Sandro remembers that Marcello had confided in him shortly before his death that he had seen Sabatini in the company of a person who could be Bradic. Ardenzi thus begins to suspect Sabatini. While Zaccardo, having learned from the police chiefs that she will be promoted, has decided to offer her position to Claudio.

Sabella is called by Cristina in tears because her partner has returned to her and is threatening her. A drug dealer questioned by Ardenzi in prison accuses Sabatini of being corrupt. Darko Bradic's body is found and Ardenzi is increasingly convinced that Sabatini is involved in this chain of crimes.

Isabella is suspended for beating Cristina's murderer after his arrest. Sandro and Ardenzi follow Sabatini and discover that he is meeting with Lele Bianchi, a customs officer from the port of Civitavecchia already known for previous drug dealing.

Zaccardo informs Ardenzi that Sabatini will be in charge of the section. Ardenzi interrogates Lele Bianchi to try to obtain evidence against Sabatini, but before he can obtain any information, Bianchi is released from prison.

Bianchi's body is found, killed by Sabatini and thrown into the river, but there's no trace of the tablet recording the drug trafficking. Claudio, promoted to head of the unit by Zaccardo, plots to have Ardenzi expelled from the station, now at war with his former friend.

Ardenzi, with the help of his team, decides to search for the gun used to kill Bradic, which Sabatini may still be hiding in the house. Roberto finally manages to confess to his daughter about her mother's true death, and their relationship grows stronger.

On the day of Valeria's and Zaccardo's wedding, he informs Ardenzi of his transfer to the Viterbo police station. The team therefore has little time to frame Sabatini: they must find the gun that killed Bradic and Clerici as soon as possible and foil the major drug trafficking that Claudio is completing with the help of Vanessa. Sandro finally discovers Sabatini's garage where the gun is kept, but this discovery could be very dangerous.

Sandro, seriously injured by Vanessa, is taken to the hospital in serious condition. Ardenzi recovers Sabatini's gun and can finally prove his guilt. Claudio, now hunted, wants to carry out the last drug trafficking and then flee abroad.