Following his battle with Gyp Rosetti, Nucky makes a peace offering to Joe Masseria while working the odds with Arnold Rothstein. Nucky heads to Philadelphia to deal with the fallout from Willie's liquor fiasco. Eli braces for the worst as Agent Knox launches his plan to bring Nucky down. Capone and Torrio reach an agreement in Cicero.

Atlantic City, 1921. In a city whose fortunes have soared in the wake of Prohibition, Nucky Thompson is paying a steep price for wielding ultimate power in 'the world's playground'. Though the 1920 election is over, Nucky finds himself the target of a federal investigation for vote tampering, and an insurrection by those he counted among his closest allies.

Chronicles the life and times of Enoch 'Nucky' Thompson, Atlantic City's undisputed czar at a time when Prohibition proved to be a major catalyst in the rise of organized crime in America. Season three begins on New Year's Eve 1922-23. The roaring '20s are about to start; though the economy is booming, alcohol has become scarce, competition is fierce, and gangster violence is heating up.