A young Italian noblewoman plots with her lover and her family to murder her abusive father leading to an uproar in the community and the Roman Catholic church set in 16th Century Italy.

Franco Sereni, a captain of carabiniers, is dismissed from service for being the proponent of "the law of the gun". He is asked to hold a private investigation of several cases of blackmailing wealthy women. Soon Sereni finds out that there is much more then just blackmailing.