The SSR arrests Edwin after tracing Howard's car from the Roxxon explosion. Meanwhile, Peggy continues her pursuit of Leviathan.
After World War II is over, Peggy finds life as a glorified secretary for the SSR boring. When Howard Stark is framed for the sale of his weapons to the enemy, he asks Peggy to help him recover them and prove his innocence.moreless
Peggy pursues Brannis and the missing bombs, and Jarvis insists on helping her. Meanwhile, the SSR gets photos of the mystery blonde seen with Spider and speaks with Hugh Jones, the owner of the imploded factory.moreless
Maggie sheds light on what led Cohle to leave the force.
Hart and Cohle are led to tent-revival minister, Joel Theriot, after a hidden image is discovered. A known sex offender is implicated in Dora Lange's murder, but Cohle is sceptical and dives into reports of old cases instead. Meanwhile, Maggie arranges a date for Cohle.moreless
Agent Knox's plan to take down Nucky begins.
Chalky and Maitland hide out at his old mentor's, Oscar Boneau. Gillian contemplates selling her business for a life with Roy.
Chalky botches the hit on Narcisse and ends up wounded himself. Van Alden saves Al Capone when the building is lit up with Tommy gunfire, and Nucky is forced into dealings with Narcisse.moreless
Julia proposes to Richard much to his delight, prompting him to ask Nucky for work. Narcisse beats Maitland for her failure.
Agent Tolliver hears what happened with Willie at the school and uses it to blackmail Eli. Narcisse arranges with Maitland to kill Chalky.
Still grieving for his brother, Al, in a fit of rage kills a policeman. Rothstein and Margaret unexpectedly run in to each other, and Willie drops out of college, enraging his father.
Eli discovers Eddie's key whilst investigating his death, but can't access what it opens, and Nucky gets some nuckie with Sally.
Knox uses torture methods on Eddie, Al's brother is gunned down, and Nucky advises Willie to stick to his false alibi.
Nucky loses confidence in Rothstein as a partner. Willie plays a revenge prank on a fellow student that goes woefully wrong, and Federal agents continue to close in on Nucky's business.
While visiting Tampa, Nucky finds himself attracted to a local bar owner. Willie tries to pinch some alcohol from Mickey's warehouse, and Richard's sister comes to his aid.
Van Alden is ordered to keep an eye on the Capone's. Dr. Valentin Narcisse arrives in town with nothing but trouble with him. Eddie demands a promotion.
Nucky reaches out to Joe Masseria after the battle with Rosetti. Gillian takes action to gain custody of her grandson. Eli's oldest son asks Nucky for career advice.
As Capone's cavalry rides in, the war starts: with firepower on the one hand and scheming to alienate Masseria from Rosetti, Nucky fights to get his business back and keep his life. Gillian takes on Gyp with her very own weapons, but sees herself overpowered; Richard poses as a one-man-army and seems to have more luck saving what's important. Meanwhile, Margaret has run off to face difficult decisions – not only about her unborn baby, but also about the future of her marriage.
Nucky doesn't get much time dealing with Margaret's affair when Gyp's men ambush him in the hotel. He flees with the wounded Eddie Kessler, and as there's nowhere safe to turn, it seems he'll be losing his last loyal man. With a price on his head, Nucky seeks refuge at Chalky's...
Gillian also has to suffer under Rosetti's willfulness when he chooses her club as a new headquarter, forcing her to lock Tommy in his room and finally even take measures against Richard, as she clings to her grandson against all common sense.
Owen makes plans with Katie as well as with Margaret, but those will turn out a whole different way after Nucky sends him to take care of Joe. Nucky too makes promises to his wife, speaking of a better future while trying to sort out his current business situation – being troubled with this, he turns down Chalky, one of his few allies left. On the political side, Gaston takes further action.
Meanwhile, Gyp has to deal with the uncertainties of nature, and Nelson "George Muller" Van Alden with the nature of uncertain dealings.