Commissioner Leonardo Cagliostro is killed while tracking a criminal, and, after a mysterious vision, he decides not to cross over to the 'other side' and continue to hunt his own killer.

Cagliostro's death affects his wife, Anna, as she struggles to deal with her pain and anger both at her father, who never accepted his son-in-law, and at her husband himself, who left her at the worst possible moment.

Cagliostro's nightmare continues as he attends his own funeral where he meets a man trapped between life and death like him who reveals to him how he can intervene in the world.

Each of Cagliostro's colleagues is hiding a secret and any one of them could be his murderer. However, the commissioner's suspicions focus on Inspector Paoletto, with whom he has always had a bad relationship.

Upset by the discoveries about her husband's secret life, Anna decides to get to the bottom of it and embarks on a personal investigation, exploring the world that Cagliostro had kept hidden from her, made up of mysterious flats and seedy clubs.

At the police station, everyone is now convinced that Commissioner Cagliostro was the mole passing on confidential information to criminals. Even Vice-Petty Officer Rambelli, who had always regarded him as a son, begins to have doubts.