Following his battle with Gyp Rosetti, Nucky makes a peace offering to Joe Masseria while working the odds with Arnold Rothstein. While Chalky is busy running the Onyx Club on the Boardwalk, the impulsive Dunn Purnsley clashes with a booking agent. Fresh-faced Federal Agent Warren Knox arrives in Atlantic City to learn the ropes from Agent Sawicki. Gillian seeks custody of her grandson, Tommy, while trying to find a “good” man to keep the Artemis Club afloat. Eli’s college-age son, Willie, turns to Nucky for career advice. Al Capone enlists his brothers, Frank and Ralph, to help him expand his business in the Chicago suburb of Cicero. Richard Harrow returns to his violent ways.
Now working as a “delivery man” for Dean O’Banion, Van Alden is ordered to keep tabs on Al Capone, joining the ascendant mobster to help keep Cicero voters “informed” at a political rally. 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, acting director of the Bureau of Investigation. Harrow fails to finish a job in Milwaukee, while Eddie demands a promotion after 11 years of service. With a business opportunity on the horizon, Nucky departs for Florida.
Nucky has reservations about investing in a Tampa land deal engineered by transplanted bootlegger Bill McCoy. While there, he meets speakeasy owner Sally Wheet. Valentin Narcisse books a sexy jazz singer, Daughter Maitland, to perform at the Onyx, and gauges Dunn Purnsley’s allegiance to Chalky. Willie, Eli’s son, turns to Mickey Doyle and his bootleg warehouse to elevate his social standing at college. Gillian agrees to pose as Roy Phillips’ wife to impress a possible partner. Harrow tries to bury his past, though not before taking care of some unfinished business with Emma.
Nucky gets to know Arnold Rothstein over a card game, and sizes up an unexpected partner for his Tampa land deal. A newly promoted Eddie Kessler gets detoured after making a train-station delivery. When one of their collectors is incapacitated, Al and Frank Capone decide to finish his route, enlisting a reluctant Van Alden to tag along. Agent Knox fills Hoover in on the Thompson operation, vowing to exploit Nucky's weakest link. Chalky is intrigued by Daughter Maitland’s presence. Dunn Purnsley goes to Harlem, and is courted by Valentin Narcisse. Willie and his college roommate, Clayton, carry a practical joke too far.
Nucky heads to Tampa to work out details of his land deal with Bill McCoy; Richard Harrow returns to Atlantic City; Agent Knox tries to gain Eli's trust; Chalky takes out his frustrations on Daughter Maitland.
Eli confronts Nucky after Willie makes an unpopular decision. Margaret has a surprise encounter at her job on Wall Street. Joe Masseria orders Lucky Luciano to return to Tampa and deal with Vincenzo Petrucelli. Gillian goes cold turkey, with Roy Phillips’ help. Still seething over his brother’s death, Al Capone tries to get Johnny Torrio to turn on rival gangster Dean O’Banion. As Chalky White and Daughter Maitland’s relationship deepens, Valentin Narcisse exerts his 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. After talking things over with Nucky, Willie reconsiders his recent life choices. Chalky throws down the gauntlet toward Valentin Narcisse, upholding his leadership on the Northside.
Nucky takes inventory after being warned of a skunk in his cellar. On the lam following a close call, Chalky and Daughter take refuge outside Wilmington with Oscar Boneau, his mentor from years ago. Gillian considers selling her mansion and starting a new life with Roy Phillips.
Eli braces for the worst as Agent Knox launches his plan to bring Nucky down. Capone and Torrio reach an agreement in Cicero. Chalky looks to settle scores. Richard steps forward to save Tommy, at Gillian’s expense