January 1920. On the eve of Prohibition, Nucky Thompson, Atlantic City's Treasurer, condemns alcohol at a Women's Temperance League meeting. Later that night, the duplicitous Nucky tells his ward bosses about the opportunity to make huge profits selling bootleg liquor.

Agent Van Alden investigates a crime he feels has been pinned on a scapegoat, convinced the Treasurer is as corrupt as the day is long. In Chicago, Al Capone shows a reporter what he thinks about Johnny Torrio being involved in the killing of mobster "Big Jim" Colosimo.

As a witness threatens to expose the partakers in the woods massacre, Nucky, Van Alden, and Rothstein take special interest in a hospital patient who may know something about the massacre. Chalky's take over of Mickey Doyle's bootleg business gets off to a rough start.

In Chicago, Jimmy bonds with one of Johnny Torrio's prostitutes and finds himself increasingly at odds with the hot-headed Al Capone. Back in Atlantic City, Nucky looks to leverage his relationship with U.S. Senator Walter Edge, as well as Jersey City Mayor Frank Hague.

Nucky deals with his jealous brother's oratory ambitions. Feeling ignored, a frustrated Margaret feeds Van Alden information. Arnold Rothstein worries about his involvement in the fixed World Series. Jimmy copes with a vicious attack orchestrated by Charlie Sheridan.

Nucky turns up the heat on Lucky Luciano after one of his ward bosses is robbed. In Chicago, Al Capone's frustration over family issues spills over into his relationship with Jimmy, who scores points with Johnny Torrio for a bold power play involving Charlie Sheridan.