After the daughter of the prominent professor Icardi (Ferzetti) goes missing an investigation is quickly commenced, much to the chagrin of commisioner Solmi (Sabato) who thinks Icardi is receiving benefits because of his status and that instead the professor should be treated like anyone else would have been treated in his place. The girl is soon found, murdered, shot in the head. The investigation gets under way and with only a few, thin, leads to go by, it's not going to be an open and shut case... The excitement unravels.