In Chicago, Jimmy bonds with one of Johnny Torrio's prostitutes, Pearl, and finds himself increasingly at odds with the hot-headed Al Capone. Back in Atlantic City, Nucky looks to leverage his political relationships with ambitious U.S. Senator Walter Edge and Jersey City Mayor Frank Hague, while Eli and Chalky go to extremes to interrogate a local KKK leader.

On the day of the annual St. Patrick's Eve dinner, Nucky deals with Eli's oratory ambitions, as well as a group of disenchanted "Leprechauns". Feeling ignored by Nucky, a frustrated Margaret feeds Van Alden information. In Chicago, Jimmy copes with the aftermath of a vicious attack orchestrated by Torrio rival Charlie Sheridan.

Nucky asks for Margaret's assistance in backing his mayoral candidate with the passage of women's right to vote, leaving her conflicted about her role. Doyle switches sides back from Rothstein, which leads Nucky to conspire with Chalky against Lansky and the D'Alessios. Angela witnesses Jimmy's violent side against her photographer friend, and considers leaving Atlantic City for good in the aftermath. Van Alden grapples with his emotions, and has encounters with both Margaret and Lucy.