The sixth episode of City of Shadows plunges us into a haunting flashback, where we witness a chilling revelation of Torrens' sexual assault on young Hector and Helena, accompanied by a haunting classical melody. The reason behind Helena and Hector's relentless pursuit of vengeance against the city's elite becomes clearer as the narrative unfolds. The same classical music echoes in the present, serving as a ominous backdrop as Helena confides in Susana that Torrens' punishment for them would be a 2-3 day confinement in the basement, devoid of food and water. However, for Susana, there would be no public spectacle.
Helena and Hector, neighbors of Georgina, watch the news with bated breath. The anticipation of the Sagrada Familia consecration, a monumental event even larger than the 1992 Olympics, looms over them. Rebeca and Milo interrogate Eva, a former teacher at La Ferradura, who is now battling cancer. Through her, they uncover Torrens' cruel methods of disciplining children – burying them alive or starving them in basements. They also learn of Hector's pyromaniac tendencies and his fixation with Gaudi, particularly the La Pedrera photo that Helena would often gaze at in Torrens' office.
As the siblings prepare for their daring plan, we witness their determination as they stockpile vast amounts of gasoline to be strapped to their bodies. Hector asserts that the man deserves it, and Helena hugs him tightly. Five days have passed since Susana's kidnapping, and footage reveals the destruction of slums in preparation for the Olympics. Parallel to this, people protest against the Sagrada Familia expansion.
Alba finally uncovers the identity of Helena and Hector Guitart, their tragic past emerging like a ghastly specter. Their mother's death sent their father into a tailspin, leading to their eviction due to the Pinto redevelopment and his subsequent death from shock. They were placed in orphanages until an aunt's death provided them with a home. Milo and Rebeca realize that the siblings' rage stems from their imminent eviction due to expropriation. They learn that Hector has been invited to the consecration ceremony as part of the Sagrada Familia staff and that he plans to set off a bomb, potentially killing the Pope and the attending politicians.
At the ceremony, Hector's nervousness peaks as he awaits the Pope's arrival. Seeing the cops sends him into a panic, and in a desperate attempt to escape, he tries to run. The cops shoot him down, but Hector sets himself on fire as his last resort and is rushed to the hospital. However, Helena is nowhere to be found.
Milo and Rebeca race to Torrens' office in Palau Guell, realizing that Helena intends to burn it down. They find her on the roof, unable to bring herself to destroy the La Pedrera photo still in the office. She is filled with shame for letting Hector down and tries to rationalize Torrens' actions. Milo pleads with her to come down, reminding her of his dead nephew, Marc, and arguing that she is not responsible for Torrens' depravity or Susana's unawareness of his atrocities. Helena hints that Susana has been buried alive and it's too late. She sets herself on fire and falls off the building.
Rebeca's belief that Susana is buried in the Guitart family mausoleum proves correct, and they are able to save Susana just in time.
In the end, Milo and Rebeca delve into Mauricio's phone, uncovering his police source - BB, a mysterious figure in the shadows. Milo brainstorms with his ex-commissioner, piecing together clues that suggest the snitch could be either Bastos or Bruno. The ex-commissioner reveals a shocking revelation: Torrens had recorded himself and other powerful figures abusing minors. They reason that the snitch is likely obstructing and covering for his patron, in case the culprits turn out to be part of a vigilante organization.
Next, Milo tests Bruno's loyalty by feigning knowledge of the snitch's identity. He then runs into Judit, who reveals that she only wrote good things in her report about him, suggesting that Bastos lied to fire him. To make matters worse, Milo's brother, Hugo, refuses to take his medication, and Sara is terrified as his schizophrenia is spiraling out of control.
As Julia reports Mauricio's death, we learn that he had two sons. It is highly likely he was reaching out to one of them in the previous episode.
After the Guitart siblings' botched plan, we cut to two days later. Rebeca is returning home, while Bruno, Mauricio's informant, has been suspended. Bastos is under investigation for his lies. Hugo is admitted to the asylum, and Milo is visibly upset. Rebeca sits with him, offering comfort in his time of grief and confusion.
