In 1920 Atlantic City, politician Enoch 'Nucky' Thompson makes arrangements to operate a liquor smuggling business during the early days of Prohibition. His driver, Jimmy Darmody, wishes to prove his usefulness.

The Feds begin to look into Nucky's affairs, his brother Eli looks to buy off Mrs. Schroeder, and Nucky essentially fires Jimmy Darmody as his chauffeur.

When a witness turns up who can link Jimmy Darmody to the woods massacre, the Feds get involved, Nucky banishes him, and Rothstein recruits Luciano to kill him.

Jimmy forges new relationships in Chicago; Nucky fetes a U.S. Senator; Chalky fingers a lynching suspect; Margaret and Lucy clash.

Nucky makes preparations for the annual Celtic Day dinner on St. Patrick's Day, and Jimmy tries to get Pearl through the trauma of her disfigurement with drugs,

Nucky investigates a boardwalk theft; Jimmy scores points with Johnny Torrio in Chicago; Margaret stands up to Lucy.

After Enoch's senile father breaks a leg in his isolated house, the brothers agree that he no longer can live alone and the house should be given to a loyal employee.

Nucky travels to Chicago and acts as kingmaker during the Presidential convention, but at home brother Eli is shot as a rival mob senses weakness in Thompson's operation.

Jimmy arrives from Chicago under his new agreement with Nucky to retaliate against a rival gang element but gets a chilly reception from Angela.

Harrow guards Margaret and the kids, Jimmy mistakenly thinks Mr. Dittrich is Angela's lover, and Chalky pretends to align himself with Lansky.

Van Alland remains suspicious of Sebso, the dying Commodore seeks a rapprochements with illegitimate son Jimmy, and Margaret leaves after a domestic argument with Nucky.

Nucky's organizational skills are put to the test as the election approaches, his judgment's questioned as he handles the Commodore's poisoning, and he reveals his part to Margaret.