The third episode of The Monster of Florence commences with news anchors revealing that Francesco is not the true "monster" after all, as the real perpetrator has struck, slaying a German gay couple. Silvia and the other detectives rush to the crime scene, their footsteps echoing through the deserted streets.
Meanwhile, a man lurks in the shadows, secretly recording and indulging in a lewd fantasy as he watches a couple having intimate moments in their car. The couple, startled by the approach of police sirens, hastily drives away, forcing the man to scurry away in embarrassment.
The next day, Silvia summons Stefano for questioning, her tone sharp as she holds him accountable for the heinous crime that has claimed innocent lives. The detectives demand the full truth about the monster, and Stefano, under duress, finally confesses that Francesco is not the culprit.
A flashback interlude reveals Stefano's relatives' disapproval of Barbara's way of dressing, their disdainful comments about her bar-hopping ways, and their plea for Stefano to rein in his wife. Stefano's father even attempts a crude sexual advance on Barbara, only to be thwarted by her threat of exposure. However, Barbara's silence is bought when Stefano's father sells the family home and gives Stefano a share of the proceeds, allowing him to purchase a new abode. Stefano's brother, Giovanni, is visibly upset by this decision.
In the present day, Stefano reveals to Maria and Giovanni that he has withheld the truth from the police. Francesco is released from prison and interviewed by a reporter, his belief that Stefano is lying to protect someone close at heart. Another flashback shows Giovanni and the rest of Stefano's family imploring him to take the fall for the murders of Barbara and Antonio Lo Bianco.
In the present, Giovanni slipped out of his house with a few household items converted into improvised weapons. As he navigated the streets, he met a woman and led her to a bar. Over drinks, Giovanni unleashed a tale of Enzo Spalletti, the once-accused Monster of Florence. Enzo was a notorious voyeur and thief, known for his peeping tom antics as he spied on couples in their cars. He claimed that Enzo had witnessed the 1981 murder, where the real monster had mutilated the female victim's genitals.
The woman's expression of unease prompted her to step outside for some fresh air. On their way back, Giovanni led her through a dark street, pointing out voyeurs lurking in the bushes, ready to pounce on unsuspecting couples. He then drove her to one of the murder sites and pretended to re-enact the killing, mimicking the gruesome act with chilling precision. The woman panicked but tried to maintain her composure as Giovanni's performance escalated. She begged him to take her home, but instead, Giovanni drove them to a secluded graveyard and tried to force himself on her.
The woman pushed him away, which only enraged him further. Giovanni opened the trunk of his car, took something out, and walked deeper into the graveyard. When the woman peered inside the trunk, she panicked at what she saw and fled to the police station.
The cops soon arrived at the Bele family home and arrested Giovanni. During interrogation, he denied any involvement in the murders, but the detectives questioned him about the deaths of Barbara and Antonio, informing him that Natalino had testified about his role in those killings. A flashback revealed Giovanni's meticulous planning and execution of the murders with Stefano and another relative.
In the present, Silvia worried that the police were once again arresting the wrong people, with both Giovanni and Mucciarini taken into custody and labeled as monsters. The episode ended with Silvia waking up to a call about another couple found murdered in their car in 1984, while Giovanni remained incarcerated.
