As Episode 4 of "The Law According to Lidia Poet" unfolds, a woman named Margherita Sangiacomo, a prestigious professor at the university, is wheeled out in a wheelchair and paraded through a buzzing crowd, her name echoed as "murderer" by the masses. The scene shifts back to Enrico's home, where at the dinner table, Jacopo senses Lidia's unspoken accusation hanging over him, though he remains clueless about its source—perhaps unaware that she has yet to confront him about his encounter with Nicole from the previous episode.
Lidia doubts Margherita's guilt in the murder, noting that she has become a target merely for not conforming to societal norms and for pursuing her studies at the university. Jacopo believes a strong motive exists, as Professor Braschi, the victim, had stolen Margherita's research. Furthermore, she had access to the poison that ultimately killed him.
In court, Lidia watches as Margherita astonishes everyone by pleading not guilty and abruptly dismissing her advocate. Following her release on bail, Margherita is confined to a convent, where she battles a fever that confines her to a wheelchair. Lidia visits her, offering the name of her brother as a potential new lawyer. During her visit, Lidia spots an array of paper swans on Margherita's table. Despite the caretaker's assertion that he saw Margherita with Braschi at 7 PM, the professor insists she left right after lunch, while Braschi was murdered around 8 PM.
The mother superior could potentially testify on Margherita's behalf, but according to the prosecutor, she is "too involved." The prosecutor also reveals a startling fact to Lidia: Margherita's mother was a prostitute, and Margherita grew up in the convent after her mother's demise. Initially opposed to taking the case, Enrico is eventually persuaded by Teresa, who sides with Lidia's reasoning. This gesture of support is a repayment for the time Lidia helped convince Marianna to buy a new dress.
While conversing with the caretaker at the convent, Lidia notices something peculiar about his drink, setting the stage for further intrigue.
Upon realizing he was unable to jot down their names in the register, she took a small sip of her drink and confirmed that he was indeed intoxicated. With a stern warning of reporting him to the authorities looming over his head, he confessed the truth: Margherita might not have been with Braschi until 7 PM. When the caretaker mentioned overhearing a heated argument between Braschi and Professor Manganelli, Lidia began to suspect that Manganelli might have a compelling motive. However, Manganelli casually admitted his dislike for the victim but provided a watertight alibi. Andrea teased Lidia about Jacopo, hinting that perhaps doubts were now creeping into her mind about whether her work truly was the paramount priority in her life.
Jacopo handed Lidia his meticulously prepared notes regarding the appeal she was drafting for the Court of Cessation. He cautioned her that the panel of seven male judges should not be instructed on what to decide, especially by a woman. He suggested that she weave her personal narrative into the appeal. Seeking clarity on substances that could linger in one's body and manifest later, Lidia sought the expertise of Ferrero, a student under Manganelli. Ferrero enlightened her about vegetable carbon, which becomes toxic upon melting.
Enthusiastically, she presented this revelation to Enrico, but he dismissed her as confused. His skepticism was justified, as Margherita could have equally administered the substance. A spark of hope ignited within Lidia as she contemplated that her gardener might have witnessed her whereabouts that day, potentially furnishing her with an alibi. As she pondered over the swans, she uncovered a stash of outdated newspapers, one of which featured Professor Antonio Borghese, who had taken his own life years ago—the same year her mother had passed away. Lidia sensed a profound connection.
Determined to uncover more, she visited Attila and Jacopo to peruse past crime reports. They discovered a pattern of prostitutes dying from an unusual poisoning during that era. That very night, Jacopo visited Lidia's room, and their passion ignited into a tender embrace. However, after their intimate moment, she broached the subject of the deceased woman, causing Jacopo to tense up. Embarrassed by her sudden shift in conversation, she asked him to return to his room and apologized for making him feel uneasy.
The following morning, at the court, Lidia confronted Margherita with her theory: Margherita had murdered Braschi. Years ago, Braschi and Borghese had collaborated on an antidote for scarlet fever, a connection that Lidia believed held the key to unraveling the mystery.
They subjected prostitutes to experimental trials, treating them as mere guinea pigs. Tragically, several of these women lost their lives as a consequence. Among them was Margherita's mother. Despite the heartache, she acknowledged the validity of the theory. Lidia insisted that Margherita speak the truth, emphasizing that "without truth, there can be no justice." If Margherita were to be acquitted, those who callously ended the lives of the prostitutes would evade accountability forever.
As the trial commenced, events unfolded according to the meticulously laid plans. However, when Margherita had the opportunity to speak, she heeded Lidia's advice and daringly exposed the cartel's dark secrets. What unfolds next remains shrouded in mystery.
While tirelessly working on her appeal under the cloak of night, Lidia witnessed Jacopo surreptitiously burying something in the yard. Driven by curiosity and concern, she descended to investigate. Meanwhile, Teresa stumbled upon Lorenzo and Marianna sharing a tender moment, their lips locked in a kiss, thus uncovering their affair. Inside the buried bag, Lidia discovered a rifle, a handgun, and a watch pocket containing a photograph of Nicole, each item hinting at deeper, darker secrets yet to be unveiled.
