The story of Osso, Mastrosso, and Carcagnosso is based on an urban legend that is still popular in Italy. The original legend dates back to the 15th century when the brothers were exiled from Spain because they murdered their sister's rapist. The brothers landed off the coast of Favignana, near the Sicilian islands, where they created new social rules and eventually founded three major criminal organizations in Italy: the Cosa Nostra (or the Mafia), the 'Ndrangheta and the Camorra (via La Mafia Uccide Solo d'Estate).
Osso, in Italian means "bone", Mastrosso means "master bone", and Carcagnosso means "heel bone".