Series 1,2Former commissioner Korrado Kattani is in Switzerland together with his wife Elza and daughter Paola who is being treated in psychiatric clinic. He"s not interested in anything, except for his daughter"s health. Meanwhile, in Sicily judge Bordonaro and policeman Altero are killed right after they manage to find indisputable proofs for huge criminal case...Series 3,4Korrado starts to help colonel Ferretti with his investigation of criminal activity of the former friend and patron Sebastjano Kannito. At the same time Korrado wins Kannito"s confidence and starts to work at his office. The most malicious enemy of Kattani - lawyer Terrazini, being afraid of revenge from Kannito and professor Laudeo, enlists the support of Korrado who leads dangerous double game... (Series 5,6Threated by inevitable scandal professor Kannito commits suicide. Before his death he reveals the truth about the existence of professor Laudeo"s illegal activity records and his secret mafia society. Korrado remains a target...