While Deputy Commissioner Ardenzi is obsessed with the investigation into his former colleague Claudio Sabatini, the Mobile Unit is launching a crucial operation called Mafia Capitale. A network of corruption and malfeasance appears to permeate the City of Rome, involving politicians, businessmen, and fixers. Through wiretaps and field investigations, the Mobile Unit is called in to clean up the mess. Ardenzi is now certain that Sabatini has returned to Rome and is trying to close the loop on him. For his part, Sabatini must resolve a major situation: he staked everything on a shipment of diamonds, and now someone has stolen them. Meanwhile, the Mobile Unit is working on the case of a young woman who was raped, and wiretaps continue in the Mafia Capitale investigation.