During a reception in a villa, wealthy banker Calandri is killed in the park with a gunshot. The gamekeeper Barra is immediately arrested, but he declares himself innocent. During the trial it turns out that the defendant had threatened the victim, guilty of courting his sister-in-law. But the deposition of a journalist present at the party soon leads to discover the existence of a dense network of equivocal relations between the victim, the guests and the servants. This judicial setting drama is allegedly the second Italian sound film after "The Song of Love", made using the RCA Photophone recording technique, and is also considered to be the first Italian detective film, a precursor to the later genre of Giallo films.