Sciascia used this story as refutation against the Mafia and the corruption, apparent to his eyes, that led all the way to Rome.
A Carabinieri captain from Parma, Bellodi, gets on the case, ruffling feathers in his contemporaries and colleagues alike. Soon he discovers a link that doesn't stop in Sicily, but goes onwards towards Rome and the Minister Mancuso and Senator Livigno.
It seems that the man shot had been warned that he should take protection from friends, which he refused; soon his building firm was sabotaged and he has a warning bullet fired at him. Which all leads to the calling.
Using faintly corrupt methods, Bellodi traps one man and uses the names given by a dead informer to trap another, who has money stashed away in many bank accounts that add up to more than his fallow fields would ever bring.
The death of an eyewitness leads to the collapse of the case against all three, which sees Bellodi taken off the case and him going sick, for ignoring the crime passionel which was the obvious answer to all the deaths.