While hosting a New Year's Eve party for 1922-23, Nucky makes a resolution that does not sit well with Gyp Rosetti, a touchy gangster with a thirst for bootleg whiskey. Margaret looks to build on the Thompson endowment at St. Theresa's Hospital, to her husband's displeasure. In the absence of Jimmy and the Commodore, Gillian builds a new business while monitoring Richard's mentoring of her “son”, Tommy. In Chicago, Al Capone is rankled by Irish mobster Dean O'Banion, and Van Alden stumbles onto a confrontation that could change his career path

Mixing business with pleasure in New York, Nucky bristles at the collection tactics of Gaston Means, a “special investigator” with ties to Attorney General Harry Daugherty. At St. Theresa's, Margaret is troubled when her altruism is met with resistance by both a patient and an idealistic doctor. Gyp extends his stopover in Tabor Heights, a town halfway between Atlantic City and New York, with an eye towards establishing a strategic foothold. Chalky and his daughter Maybelle fail to agree on her future with Samuel; Eli gets a new boss and faces new realities at home; a major liquor shipment takes an unexpected detour.

Disturbed by a recent nightmare and Billie's absence, Nucky reluctantly joins Margaret to receive a high honor from the Church. Meanwhile, Gyp makes a deal with Nucky for a onetime liquor shipment, though the mobster's longtime intentions remain very much up in the air. Van Alden regrets trying to socialize with his co-workers; Margaret takes her women's-clinic pitch to a higher authority; Lucky and Meyer protect their investments; Richard sets the record straight with Mickey, and with Nucky.

After tracking down a liquor thief, Nucky and Owen spend a long night hiding out from the fedswith the precocious perp. In his boss' absence, and with Rothstein fuming over a late delivery, Mickey overrules Eli to make a routing call that will have far-reaching consequences for Nucky and Gyp. Margaret encounters a familiar face while promoting Dr. Mason's classes at the new women's clinic at St. Theresa's. In New York, Lucky haggles with Joe Masseria over heroin splits, while in Chicago, Capone's feud with O'Banion heats up when one of his collectors gets roughed up on the South Side.

After venting with Nucky about his liquor travails, Rothstein sends Gyp an unequivocal message in Tabor Heights. In Washington, Gaston Means sees opportunity in a Senate investigation of Harry Daugherty and the Justice Department. Billie gets a new co-star to revive her faltering show; Van Alden and Sigrid receive an unexpected visitor; Gillian worries about keeping her business afloat in Jimmy's absence; Margaret has Awkward moments at the hospital and, later, at Madam Jeunet's.

After being detained in Washington by Daugherty's henchmen, Nucky approaches Esther Randolph, his onetime nemesis, and later entertains an intriguing proposition from Gaston Means. In Atlantic City, Margaret copes with Teddy's demons, while Owen investigates a suspicious fire; Gillian feuds with Lucky and finds a surrogate for Jimmy; and Richard connects with pugilistic vet Paul Sagorsky and his daughter Julia.

On Easter Sunday, Eli looks to get back in Nucky's good graces at a Thompson family reunion. While Richard and Tommy spend the day as guests of the Sagorskys, Gillian stays at home and makes a sacrifice to improve her future. In New York, after dinner and prayers, Gyp heads downtown in search of a blessing - from Joe Masseria.

Gillian makes her peace with Jimmy's passing, though not with Nucky, as Gyp arrives to play ally. Working off his debt to O'Banion, Van Alden attends a meeting with Capone and Torrio; later, after a workplace meltdown, he considers Sigrid's case for staying put versus resuming a life on the lam.With help from Gaston Means, Nucky pays an unscheduled visit to Andrew Mellon, offering the Treasury Secretary a recommendation and a business proposal. Margaret makes a stand on birth control; Nucky and Owen shop for a birthday pony; Billie eyes a future on the silver screen, to Nucky's chagrin.

Reeling from Gyp's most recent attack, Nucky vows to eliminate his nemesis through a coalition of familiar partners. In Washington, the arrest of a high-profile bootlegger puts Daugherty and Jess Smith on the hot seat. Emily gets a scaled-down birthday party; Gillian blames an absent Harrow for Tommy's latest misadventure; Gyp decides to buy a town's silence; Broadway mourns a fallen star.

Nucky reaches out to Gaston Means to keep Jess Smith quiet in Washington, and enlists Owen to neutralize Gyp's alliance with Joe Masseria in New York. Margaret considers alternate futures, at the hospital and at home; Van Alden's side business backfires; Gyp fumes when a shipment comes up short; Harrow coerces an apology for Julia; Chalky sees opportunity in the ashes of a boardwalk institution.

Gyp makes his move in Atlantic City, forcing Nucky and Eddie to seek refuge with Chalky. With the Artemis Club overrun by Rosetti thugs, Gillian contemplates a business future that includes an unwelcome partner. Luciano makes a deal he'll come to regret; Harrow loses his house privileges.

A gang war erupts in Atlantic City, with Gyp and nine men of his own and 40 of Joe Masseria's against Nucky, Eli, Capone's Chicago crew, and Chalky's men. Gyp's holed up at Gillian's; Nucky at a lumber yard. It's a war of attrition, with Nucky having to keep Capone and Chalky's men from hugging each other while he negotiates with Rothstein by phone. Rothstein runs his own game with Luciano, Lansky, and heroin, Margaret calls on an older couple, and Richard is out there somewhere focused on protecting Tommy.