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.