Most Mafia stories ask how the empire was built. The Last Don’s Mistress asks a different question: what happened afterward? Joseph Bonanno was one of the last surviving links to the old Mafia era of Al Capone and Lucky Luciano. As that generation receded into history, Bonanno lived to ninety-seven. Theresa’s memoir captures a side of Mafia history rarely recorded: the private life of an aging don, told by the woman beside him. But this is also Theresa D’Antonio’s story: a memoir of love, loyalty, family, and migration to America during a time of profound change, told by a woman who spent twenty-five years inside Bonanno’s private world.