Having survived his battle with Gyp Rosetti, Nucky makes a peace offering to Joe Masseria while working the odds with Arnold Rothstein. Chalky prepares to open the Onyx Club on the Boardwalk, and a new prohibition agent, Warren Knox, arrives in Atlantic City.

Following Dean O'Banion's orders, Van Alden muscles for Al Capone. Harlem gangster Dr. Valentin Narcisse arrives in Atlantic City, clashing with Chalky and Nucky over the loss of an employee. In Washington, Agent Knox aligns himself with J. Edgar Hoover.

Nucky has reservations about investing in a Tampa land deal engineered by transplanted bootlegger Bill McCoy. Valentin Narcisse makes his mark at the Onyx Club, and Richard Harrow tries to bury his past, though not before dealing with some unfinished business with Emma.

Nucky gets to know Arnold Rothstein over a card game and sizes up an unexpected partner for his Tampa deal. Al and Frank Capone enlist Van Alden to tag along on one of their "collections". Knox fills Hoover in on the Thompson op, vowing to exploit Nucky's weakest link.

Nucky heads to Philadelphia to deal with the fallout from Willie's liquor fiasco. Eddie Kessler is detained by Agent Knox, who uses physical and psychological tactics to elicit information. Van Alden is recruited by the Capones to pay a visit to local factory workers.

Nucky heads to Tampa to work out details of his land deal with Bill McCoy. Richard Harrow returns to Atlantic City and makes a confession to an ailing Paul Sagorsky. Having lost J. Edgar Hoover's confidence, Agent Knox finds a new way to gain Eli's trust.

Eli confronts Nucky after Willie makes an unpopular decision. Joe Masseria orders Lucky Luciano to deal with Vincenzo Petrucelli. Al Capone tries to get Johnny Torrio to turn on Dean O'Banion while Valentin Narcisse exerts control over Dunn Purnsley and the Northside.

Nucky's shipment from Florida arrives with some unexpected cargo. Eli is backed into a corner after Agent Knox uncovers some new dirt on the Thompsons. Chalky throws down the gauntlet toward Valentin Narcisse, upholding his leadership on the Northside.

Nucky refuses to back Chalky in his conflict with Narcisse. Julia ponders her options after Gillian makes her custody case in court. In Cicero, Van Alden stands up to Capone and comes clean to O'Banion. Rothstein looks to trade an insurance benefit for a cash infusion.

Tipped off by Sally Wheet, Nucky enlists Eli and Agent Knox to check out extra cargo in Florida shipments. Margaret considers making a deal with Rothstein to improve her family's living conditions. Capone grows suspicious of Torrio, and Eli makes peace with Willie.

Nucky takes inventory after being warned there's a skunk in his cellar. On the lam after a close call, Chalky and daughter take refuge outside Wilmington with Chalky's old mentor, Oscar Boneau. Meanwhile, Gillian considers starting a new life with Roy Phillips.

Eli braces for the worst as Agent Knox sets in motion his plan to take down Nucky. Meanwhile, Capone and Torrio reach an agreement in Cicero, Chalky looks to settle his scores, and Richard Harrow steps forward to save Tommy, at Gillian's expense.

New Year's Eve 1922 and Nucky makes a resolution that does not sit well with Gyp Rosetti, a touchy gangster with a thirst for bootleg whiskey. Margaret, meanwhile, looks to build on the Thompson endowment at St. Theresa's Hospital.

Mixing business with pleasure in New York, Nucky bristles at the collection tactics of Gaston Means, an investigator with ties to Daugherty. Gyp makes a power play in Tabor Heights and a major liquor shipment takes a detour.

Nucky reluctantly joins Margaret to receive a high honour from the Church. Meanwhile, Gyp makes a deal with Nucky for a onetime liquor shipment, though the mobster's long-time intentions remain very much up in the air.

After tracking down a liquor thief, Nucky and Owen spend a long night hiding out from the Feds with the perp. 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 Washington, Gaston Means sees opportunity in a Senate investigation of Harry Daugherty and the Justice Department.

After being detained in Washington, Nucky approaches Esther Randolph and later entertains an intriguing proposition from Gaston Means. In Atlantic City, Margaret copes with Teddy's demons and Owen investigates a fire.

On Easter Sunday, Eli looks to get back in Nucky's good graces at a Thompson family reunion. In New York, after dinner and prayers, Gyp heads downtown in search of a blessing from Joe Masseria.

Working off his debt to O'Banion, Van Alden attends a meeting with Capone and Torrio. Nucky pays an unscheduled visit to Andrew Mellon, offering the Treasury Secretary a recommendation and a business proposal.

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 in the hot seat.

Nucky reaches out to Gaston Means to keep Jess Smith quiet in Washington, and enlists Owen to neutralise Gyp's alliance with Joe Masseria in New York. Margaret considers alternate futures, at the hospital and at home.

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.

Season finale. Desperate to weaken Gyp's union with Masseria & reclaim Atlantic City, Nucky cedes control of one of his prized assets to Rothstein. Margaret decides to end one relationship & considers resuming another.

Nucky recalls his Atlantic City roots and plots a post-Prohibition future in 1931 Cuba. Margaret finds herself in the hot seat on Wall Street when her boss decides his own future. Lucky Luciano sets in motion a plan; one that reverberates with Nucky all the way in Cuba.

Back from Cuba, Nucky meets with "Boss of Bosses" Salvatore Maranzano, sending a message to Lansky and Luciano. In Chicago, Eli and Van Alden are tasked by Al Capone's top man to recoup money lost during a federal raid. Fresh out of law school, Willie has an interview.

Margaret faces a dilemma at the bank as a result of her association with Arnold Rothstein, while Nucky entertains a prospective business partner from Boston. Luciano and Siegel meet with Narcisse in Harlem, but encounter resistance after promising business as usual.

Nucky and Margaret find common ground in Atlantic City when they face a shared dilemma, while Lucky Luciano meets Al Capone in Chicago and encounters an old adversary. Elsewhere, Sally Wheet makes a payment in Cuba as she grows fearful of a grass-roots uprising.

Chalky returns to Atlantic City with vengeance on his mind. Nucky arranges a meeting with Maranzano to discuss the Luciano threat. Eli's reunion with June takes an unexpected turn after a dinner party. Capone looks to relocate his operation. Bad news arrives from Cuba.

In Harlem, Chalky encounters Narcisse in hopes of setting Daughter Maitland free. Federal Agents enlist Eli and Van Alden to help take down the Capone organisation. Pained by a recent loss, Nucky turns to the bottle, and the company of a pair of barflies.

Nucky, at war with Luciano, looks to hold onto his assets in Atlantic City. Willie and Eli become involved in Nucky's war. Maranzano meets his fate. Nucky reads Gillian's letter from the hospital.

Nucky looks to relocate to Manhattan from Atlantic City. Margaret impresses Nucky and a grain-company stockholder. Luciano tends to unfinished business while establishing a mob commission. William shares underworld details with his boss, the U.S. Attorney.