In Sicily, truck driver Salvatore Colasberna is murdered while delivering a load of cement to a highway construction project. The murder takes place within sight and earshot of the house of Rosa Nicolosi (Cardinale) and her husband. Police captain Bellodi (Nero) hears that there may be irregularities in the construction of the highway that amount to corruption. He is also told that Rosa has loose morals, though she denies it strenuously and claims that she has been faithful to her husband.