It is 1935, Alberto Rinaldi is killed, only apparently a common provincial doctor. In reality, a medical luminary of the time. Thanks to his treatment, in fact, his patients included prominent personalities in Italy, Europe and even America. Despite the attention of the newspapers and the victim's family, the investigation and trial turn out to be a farce, nothing is clarified by the courts and everything slips into oblivion. Fourteen years later, in 1949, President of the Republic Luigi Einaudi wants to confer the nomination of life senator on the great composer and conductor Arturo Toscanini. On the maestro's past, however, there is only one shadow: his name appears among the documents of the investigation into Rinaldi's murder, and in that delicate historical phase of republican transition it is necessary that no public figure has skeletons in the wardrobe. But why did Rinaldi's death have anything to do with Arturo Toscanini? What was the relationship between the scientist and the maestro? Colonel Luigi Mari, a heroic figure of liberal anti-fascism, flanked by the young Lieutenant Barbetti, is tasked with shedding light on a mystery that has been going on for too long.