The Donnellys are four young, working-class Irish brothers involved in New York City's organized crime. Detectives investigate Joey Ice Cream, a life-long friend of the Donnellys who introduces the four brothers, setting the scene for the series.
Kevin Donnelly feels that he's on a hot streak, but when his gambling begins to add up, the eldest Donnelly brother, Jimmy, is forced to kidnap the bookie that Kevin owes money to. When the news of the kidnapping spreads around the neighborhood, connecting the Donnellys to the incident, the youngest brother, Sean, pays the price for having the Donnelly name. Meanwhile, Tommy Donnelly, the most reliable of the brothers, has to sacrifice for his family when Jimmy's plan lands Sean in the hospital.