The miniseries chronicles the historical roots of the original Five Families that led to the formation of the modern American mafia. The story begins in 1905 and spans 50 years to trace the rise of Charles "Lucky" Luciano, Meyer Lansky, Benjamin "Bugsy" Siegel and other notorious gangsters from their beginnings as a neighborhood gang of teenagers to murderous entrepreneurs and bootleggers who organized the criminal underworld and turned it into an American institution.