Thou Shalt Not Kill Season 1

The dead body of 15-year-old Sara Damiani is found in a flooded basement. Her father, Giancarlo, receives the news while at a television studio where he is about to broadcast a national plea for help regarding his daughter's disappearance. In the homicide division of Turin's police force, Chief Inspector Valeria Ferro grabs the reigns of the investigation.

The investigation into Sarah Daminai's death continues, was it an accident or murder? What could the motive be for murdering an innocent teenage girl? As Valeria hunts for the truth, she must also deal with the fact that her mother, Lucia, has been released from prison, convicted seventeen years earlier for a terrible crime.

The homicide of Guglielmo Mantovani appears to be the tragic consequence of a home robbery gone wrong. However, Guglielmo's three children seem to be hiding something; Leonardo works in the family bank, Eva is a suffering artist, Filippo is an eternal teenager... not one of them seems particularly distraught.

Mantovani family secrets start to unravel which adds further intrigue and suspension into the murder of Guglielmo Mantovani. Having discovered that her mother, Lucia, is about to come home, Valeria packs her bags and goes to live with Giorgio Lombardi; her boss, her boyfriend, and, the man who arrested her mother seventeen years earlier.

On a dreary, rainy day, Graziano Torri calls the police; his wife, Alessandra, who has just told him that she is pregnant, is missing. When Valeria arrives at the woman's home she finds a mysterious and recently dug hole...

Guido, Valeria's brother urges her to stop withdrawing from her family, which once again includes Lucia. After a particularly tense altercation, Lucia understands that her family will never be able to forgive her and that perhaps it would be best for her to disappear.

The body of a twenty-two-year-old women is found on the banks of the Po. Her name was Stefania and she worked in a nearby Benedictine monastery. Without overlooking the obvious trail that leads to the halls of the monastery, Valeria questions Stefania's lover, Michele.

In addition to trying to discover who murdered Stefania, Valeria also must figure out where her mother is. Valeria, locates Lucia, at the home of Monica, Lucia's former cell mate. Valeria, asks her mother to return home.

A young Egyptian woman, Amina Mansour, is found dying in the hammam where she works after having been attacked with a knife. Amina has an Italian boyfriend and dresses in western clothes, it occurs to Valeria that this may not be taken very well by her family which is still extremely anchored in tradition.

Just when peace seems to have been restored to the Ferro household, Monica, Lucia's former cell mate, pays a visit to the house and upsets the harmony that mother and daughter were slowly trying to re-establish.

Arianna Lancise finds her 4-year-old daughter dead in the car, where she had left her for just several minutes. The lack of clues leads the police and public opinion to blame Arianna, but Valeria is convinced that she is completely innocent.

While Valeria attempts to prove the Ariana's innocence, Monica confesses that Lucia, has always been innocent as well - she wasn't the one who killed her husband and Valeria's father, Mario. Who did?