Nucky is awash in memories from pier-boy days growing up in 1884 Atlantic City, when the young Nucky caught the eye of the Commodore. In 1931 Cuba, Nucky joins Sally Wheet and, with a U.S. Senator in tow, forges ties with Bacardi Rum in hopes of Prohibition's repeal in the U.S. Working on Wall Street, Margaret finds herself in the hot seat when her boss, facing an internal investigation, decides his own future. Down but never out, Chalky seizes an opportunity to extricate himself from a difficult situation. In New York, Lucky Luciano sets in motion a bold plan that reverberates all the way to Nucky in Cuba.
Back from Cuba after a dangerous encounter, Nucky pays a visit to the now-retired Johnny Torrio, who agrees to broker a meeting with the new "Boss of Bosses," Salvatore Maranzano. In Chicago, Eli and Van Alden are tasked by Mike D'Angelo, Al Capone's new right-hand man, to recoup money lost during a federal raid by Eliot Ness. Fresh out of law school, Willie Thompson has a job interview. Rebuffed by a group of would-be financiers, Nucky dines with Tonino Sandrelli before sending a message to Lansky and Luciano. In 1884, a young Nucky deals with the death of his sister, Susan, while his father has a standoff with the Commodore.
Chalky heads in a new direction after assessing his latest partnership. In New York, Margaret finds herself in a quandary as a result of her association with Arnold Rothstein. Nucky hosts a prospective "big fish" partner from Boston. Luciano and Siegel meet with Narcisse in Harlem, promising business as usual, but encounter resistance. In 1884, young Nucky is privy to the passion of a hotel guest, and flirts with a young girl.
Facing a shared dilemma, Nucky and Margaret find common ground in Atlantic City. Luciano encounters an old adversary while meeting with Capone in Chicago. Sally Wheet makes a payment in Cuba amidst concerns of a grass-roots uprising. In 1884, young Nucky shows young Eli how the other half lives, and takes another step up the Commodore's ladder.