The events of the crime series "La piovra" unfold on the island of Sicily, where the head of the criminal investigation department, Marinéo, is killed. The local mafia "family" is accused of this crime. On the same day, another death occurs: Marquise Pecchi Shaloya takes her own life. Experienced Commissioner Corrado Cattani arrives on the island to replace his deceased colleague. During the investigation, he meets a young drug addict named Titti, who turns out to be a relative of the late Marquise, and he falls in love with her.