Sante Moras is a former police officer who works as a prison guard in Sardinia. His life takes a dramatic turn when he is wrongfully accused of the murder of Virdis, an inmate convicted of torturing and killing a 15-year-old girl, whose body bore a symbol known as the "devil's tail." After finding Virdis dead during his shift, Sante realizes he has been framed and decides to flee to prove his innocence. During his escape, he is pursued by Commissioner Tommaso Lago and finds support in investigative journalist Fabiana Lai, who is investigating a mysterious ring of missing girls. Together, they uncover that behind the murder lies a much larger and more dangerous criminal organization involved in human trafficking. As Sante seeks to uncover the truth and clear his name, he must also confront the imminent danger that other girls could become victims of the same criminal network.