It's 1921 and after rigging the Atlantic City mayoral election, Nucky appears to be in control of the city. However, Nucky's grip soon begins to unravel as he is arrested for election fraud and members of both his inner circle and family begin to question their allegiances, while mobsters including Arnold Rothstein, Lucky Luciano, Meyer Lansky, and Al Capone wait in the wings, looking for the right opportunity to grab a bigger piece of Nucky's pie.