A gunshot is heard and the figure running for the bus is shot twice in the back, with what is discovered as a lupara (a sawn-off rifle that Sicilian Mafia clans use for their killings).

A Carabinieri captain and former Civil War partisan from Parma, Bellodi, gets on the case, ruffling feathers in his contemporaries and colleagues alike.

Moreover Bellodi uses the names given by an informer (Calogero Dibella, known as "Parrinieddu"), who was killed in retaliation, to arrest the local mafia boss don Mariano Arena, who has money stashed away in many bank accounts that add up to more than his fallow fields would ever bring.

The death of Paolo Nicolosi, a witness to the presence of the killer near the crime scene, is attributed to his wife's affair.

The novel was adapted into the film of the same name in 1968 by Damiano Damiani, starring Franco Nero as Captain Bellodi and Claudia Cardinale as Rosa Nicolosi.