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 Darmody, a recently returned WWI vet, that his appointment as "Man Friday" to the new Chief Clerk of the Fourth Ward, Paddy Ryan, will lead to bigger things. Jimmy, meanwhile, has higher aspirations and ends up making an alliance that could have dire consequences for both him and Nucky.

A 30-minute documentary from HBO, "Atlantic City: The Original Sin City." It's a companion piece to the series, and originally aired on HBO just prior to the series premiere. It includes interviews with many of the experts on Atlantic City history, including Nelson Johnson (author of Boardwalk Empire), Allen "Boo" Pergament, Heather Halpin Perez, Ralph Hunter, Vicki Gold Levi, Turiya S. A. Raheem, and Bryant Simon. It also includes executive producers Martin Scorsese and Terence Winter, as well as the research advisor for the series, Ed McGinty.

Fresh from the realization that she is a member of the Fae, Bo is approached by a strange client, Will, a real life Will O' the Wisp. The storehouse of jewels he's collected over the centuries has been stolen... by a human! While this line of work is foreign to Bo, Will offers her an irresistible payment - information about where she might have come from. As Bo gets involved in the recovery of Will's gems, she finds the shocking truth about the thief... and the weird and deadly forces that seem to also be on the trail of the jewels.

Peggy is forced to face some unpleasant facts about a client's discriminatory business practices. Don and Faye's burgeoning relationship is tested when Sally runs away from home and turns up at the office. Roger tries to rekindle his affair with Joan.

Longworth investigates the death of a famed treasure-hunter who was after a Spanish ship believed to contain billions of dollars in booty. Longworth must figure out if the victim was close to finding the treasure and if that's what got him killed. Callie's passion for treasure hunting lore sets her and Longworth on an adventure that just might change their lives.