The Legacy of the Bones

Amaia Salazar returns to the Baztán Valley to investigate a series of suicides that resemble a pattern from a murder case she solved a year earlier. She suspects the cases are linked to the old Northern Spain murder and its dark implications. The fresh investigation reopens old wounds, including the strained relationship with her mentally ill mother Rosario.

Just before the trial for Jason Medina, he dies by suicide in the City Court, leaving behind a cryptic note. Amaia's water breaks at the courtroom, and she gives birth to her son Ibai in the hospital. This dramatic moment intertwines her professional crisis with a personal one as she becomes a mother during the investigation.

Four months later, Amaia is reinstated to active duty and tasked with leading two investigations that must be handled discreetly. The cases hint at deeper connections to the earlier murder and looming danger for her family. Her focus shifts to balancing motherhood with a growing sense of peril around her.

During the new assignments, a small church is profaned and a baby's severed arm is found on the altar. The grisly discovery raises questions about ritual acts and whether the past murder is resurfacing. Amaia begins to see that the new crimes may be connected to her own history.

In Logroño, a man incarcerated for murdering his wife commits suicide and leaves a note with the word Tartalo. Amaia starts linking this 'Tartalo' clue to previous bone findings and the old pagan legend. The case deepens the mystery and pushes her to look for hidden connections.

Amaia theorizes that Tartalo refers to a pagan myth where a giant consumes Christian babies, tying the recent violence to the pile of bones found last year. The revelation expands her investigation beyond ordinary crime and into ritualistic history. She begins to see a through-line connecting past and present acts.

Amaia and her family relocate to Elizondo after Aunt Engrasi mentions the grandmother’s abandoned house. She meets the quiet groundskeeper who seems distant and unresponsive when greeted. The new setting begins to reveal hidden tensions and secrets within the family.

Aunt Engrasi uses tarot cards to warn of an evil presence surrounding Amaia, while she reaches out to her former FBI mentor Aloisius Dupree for help. The warnings add a supernatural tint to the investigation and pressure Amaia on her personal life. Her relationship with James strains as she becomes more consumed by work.

The investigation takes an abrupt turn when the newborn baby with an amputated arm is revealed to be Amaia's twin sister, a sister she did not know existed. This shocking genetic twist reframes Amaia’s sense of family and destiny. The revelation intensifies her drive to solve the case.

As Amaia investigates family secrets, Rosario attacks a nurse with a scalpel and a blood-written Tartalo message is found under the bed. Padre Saralosa reappears, pressing to move Rosario to his university hospital. The enigma deepens as Amaia confronts her mother's possible imminent danger.

Amaia discovers that her mother Rosario is connected to a pagan sect that practiced human sacrifices, and that most of the crimes are tied to Amaia's own bloodline. She learns that the psychiatric doctor is the groundskeeper’s estranged son involved in the ritual acts. The investigation becomes a personal confrontation with her family history.

In a tense confrontation, Rosario and Doctor Berasategui plan to sacrifice Ibai; Amaia shoots to stop the ritual. Rosario realizes that Amaia’s child is a boy and not a girl as she intended, and she ultimately disappears, leaving Amaia with the trauma of her family past unresolved but resolved for the moment.

Amaia places her twin sister's bones in the backyard of the large house to rest, completing a personal ritual of closure. Yet Rosario remains at large, a lingering threat that haunts Amaia.