January 1920. On the eve of Prohibition, Atlantic City's Treasurer, Nucky Thompson, condemns alcohol at a Women's Temperance League meeting, where he is noticed by Margaret Schroeder, a pretty, pregnant housewife who comes to him for help in getting her abusive husband Hans a job. Later that evening, the duplicitous Nucky privately tells his ward bosses about the opportunity to make huge profits selling bootleg liquor. At a countdown-to-midnight blast at Babette's Supper Club, he assures Jimmy D
Nucky is paid a visit by straight-arrow Agent Nelson Van Alden, who feels that Nucky has pinned a crime on a scapegoat. After using his recent windfall to buy presents for his wife Angela and mother Gillian, Jimmy is forced to pay Nucky a larger sum of money. Margaret is visited by both Van Alden and Nucky's brother, Sheriff Elias Thompson, each seeking a different side of her story as to the death of her husband. After the funeral of James "Big Jim" Colosimo, Chicago gangster Al Capone has a vi
Nucky makes a deal with African-American gangster Chalky White to handle the repackaging and distribution of bootlegged whiskey, a decision that quickly turns deadly for Chalky's gang. Margaret is given a job at a boutique through Nucky's connections, and crosses paths with his mistress Lucy. Agent Van Alden learns through a brutal interrogation that Jimmy was involved in the shooting in the woods, a discovery that forces Nucky to make a decision on Jimmy's future in Atlantic City.
Nucky celebrates his birthday and uses the event to try and expand his influence over both the Mayor of Jersey City and a United States Senator. Margaret is tasked with delivering a dress to Lucy, and finds solace from her disillusionment by shoplifting lingerie. Chalky exacts revenge on a local Ku Klux Klan leader for a lynching. Jimmy and Capone expand their business operations by taking over territories from a local Irish gangster, resulting in vicious consequences for Pearl, a prostitute Jim
Nucky prepares for St. Patrick's Day, but finds himself at odds with an increasingly antagonistic Eli. The attack on Pearl has devastating consequences for both her and Jimmy. Gillian proposes to Angela, the mother of Jimmy's son, that she take over raising the child. Margaret, feeling slighted by Nucky, passes information to Agent Van Alden that disrupts both his business partnerships and the annual Celtic Dinner – a decision which leads to a tense late-night encounter between the two.
Nucky investigates a boardwalk theft against one of his ward bosses, which leads him to directly confront Luciano – who has been conducting an affair with Gillian. Margaret embraces her new role as Nucky's mistress, which gives her the nerve to stand up to Lucy. Jimmy scores points with Johnny Torrio and antagonizes Capone in Chicago with his definitive solution to the Sheridan gang dispute. Van Alden struggles with his superior's instructions and his growing obsession with Margaret.
Nucky purges some painful childhood memories with the upcoming sale of his father's home. Jimmy forms an alliance with Richard Harrow, a former Army sniper heavily scarred in the war, which allows him to find justice against the man who disfigured Pearl. Luciano and Rothstein protégé Meyer Lansky enters into an alliance with the D'Alessio brothers to set up a new bootlegging business, bankrolled by robbing Nucky's business ventures. Angela Darmody pursues a new love affair, while Lucy and the Co
Nucky visits Chicago for the Republican National Convention, where he finds himself intrigued by the candidacy of Warren G. Harding over more established candidates. The D'Alessio gang moves in on Nucky's territory at the expense of Eli, who has been watching over his brother's affairs. Margaret finds herself entangled in Nucky's business, while Van Alden struggles with his wife's desire for a child. Rothstein prepares for legal trouble over his role in fixing the 1919 World Series. Nucky asks J
Nucky is forced to readjust his political alliances because of a Democratic mayoral candidate promising to wipe out corruption. Jimmy returns from Chicago to deal with the D'Alessio gang, which has allied with Rothstein to import Scotch from Europe through Atlantic City, but is arrested by Agent Van Alden for the massacre in the woods. Margaret intercedes with Nucky on Madame Jeunet's behalf, while Angela finds her romantic and artistic ambitions halted by Jimmy's return.
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 expanding role as his mistress. Doyle switches sides back from Rothstein to Nucky, which leads him to conspire with Chalky against Lansky and the D'Alessios. Angela witnesses Jimmy's violent side against her photographer friend, and plans a better future with his wife. Van Alden grapples with his emotions, and has forceful encounters with both Margaret
Nucky has emotionally charged conversations with both Margaret and Eli over his business and the killing of Margaret's husband, leading to dramatic shake-ups in his personal and political lives. Jimmy meets with his dying father for the first time in years, and in the process reevaluates his relationships with Nucky and both his parents. Van Alden and Agent Sebso's working relationship is pushed to the limit by Van Alden's suspicions, ending after a definitive confrontation at a river baptism. A
Nucky faces Election Day in Atlantic City and pulls out all the stops to keep power in Republican hands. Torrio brokers a discussion between Nucky and Rothstein to resolve their growing gang war, as well as Rothstein's looming federal indictment over the World Series. Both Jimmy and Eli voice their growing resentment towards Nucky, and find they have an ally in the equally embittered Commodore. Van Alden seeks a sign on whether or not to leave Atlantic City, but receives unexpected news from Luc