It's Nucky's birthday and Margaret is asked to bring Lucy a special dress for the occasion. Chalky interrogates the local Klan leader to see if he was responsible for the lynching. Jimmy joins Al Capone in expanding Johnny Toriano's territory.
Snubbed by Nucky, Margaret goes to Agent Van Alden to report illegal beer being imported. Van Alden makes an arrest and shuts down the Celtic dinner at which Nucky and Eli were hoping to impress their Irish brethren. Meanwhile Jimmy takes care of Pearl as she recovers from her wounds.
Nucky heads to Chicago for the Republican Convention. He does his homework and throws his support behind Warren Harding. Meanwhile Eli is shot and Nucky is forced to return but not before asking Jimmy to return and help him. Agent Van Alden's wife wants to have a baby but can't. Nucky asks Margaret to look after his ledger and she looks inside to find the records of his illegally imported alcohol trade.
Jimmy returns home and is immediately arrested. Angela isn't too happy to see him return. Nucky begins to make plans to kill the men who robbed the casino and to replace both Eli and the Mayor by election time. Margaret learns that Madame Jeunet may lose her shop and decides to see if there's something she can do about it.
Nucky asks Margaret to give a speech endorsing his choice for Mayor. Agent Van Alden is blamed for the death of the witness to Jimmy's murders. Van Alden goes to see Margaret and tries to convince her to leave Nucky. Richard Harrow now lives with her to protect her and the children. Jimmy lays a beating on the photographer when Tommy points to 'Mommy's Kissing Friend.' Afterwards Mary convinces Angela to run away with her to Paris. Mickey Doyle betrays his new associates to Nucky.
Margaret confronts Nucky about her husband's death, they have a huge row and she leaves. Jimmy discovers that his mother has been poisoning his father (the Commodore). Agent Van Alden refuses to believe Agent Sepso's story and is determined to make himself right with God at the same time.
Torio arranges a meeting between Rothstein and Nucky. Nucky agrees to make the World Series indictment disappear in exchange for the death of the Delassio's and one million dollars. In the meantime the Republicans win the elections both in Atlantic City and with Warren Harding becoming President. Agent Van Alden prepares to leave his post and then gets unexpected news from Lucy. Jimmy, Eli and the Commodore sit down to plot against Nucky while Margaret returns to him.