Jones is broke. His girl is giving a birthday party, and her various suitors give her costly presents. Jones finds a beautiful lavaliere, which be gives to Mabel, and wins her heart. He is chosen as the foreman of a jury, and when petty offenders are brought to trial turns a deaf ear to all pleas for mercy, gaining the hatred of the other jurors. Finally a man is brought up who is to he tried for stealing the necklace Jones found. A strong case is shown, and all the other jurors want to find him guilty, but Jones holds out for an acquittal. Mabel comes into the court room and sits alongside of the complainant. The necklace is seen and an uproar takes place. Jones is accused as a thief and in a highly melodramatic manner takes a huge vial from his pocket, drinks the contents and falls back dead.

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.

In the first of a potential series of films inspired by the real-life experiences of Los Angeles police officer turned bestselling author Joseph Wambaugh, an on-the-skids detective, with memories of having accidentally shot and killed his partner while they were pursuing a pair of bank robbers, tries to put his life back in order.