Thomas Shelby's war with the Lee family of gypsies escalates and Campbell puts further pressure on him to deliver the stolen guns. Meanwhile, John Shelby plans to marry a former prostitute, but Thomas suspects that she's still on the game.
John tells his family members that he is getting married to the prostitute Lizzie Stark. Finn Shelby tells them that they've been done over.
When they return to the house, they realise that there's a pair of wire-cutters, a reference to their war days, which means that there's a hand grenade somewhere around there. Thomas Shelby realises the hand grenade is in his car, and saves his brother Finn from the grenade when Finn Shelby decides to pretend to be Thomas by climbing into his car.
Thomas goes to the Lee family to settle the dispute between the Lees and the Shelbys once and for all. Claiming that he is related to the Lee family on his mother’s side, Thomas tells Zilpha Lee that he will be betraying Billy Kimber and that he needs men to help.
Polly Shelby tells Thomas she received an address from an acquaintance anonymously, and tells him she has a strategy to deal with the Freddie Thorne situation. Thomas delivers the address of Stanley Chapman (a Communist man holding 200 pounds in cash given to the Communist Party by the Russian government) to Inspector Campbell, instead of Freddie Thorne.
Campbell threatens Thomas and his entire family, if Thomas does not give him the stolen guns in time before the Inspector gets dismissed from his position. Campbell promises that in exchange for the address, he will let Freddie Thorne and Ada Shelby leave the city. As Campbell leaves, Thomas draws his gun and aims it at his back, but does not fire.
Campbell and his men arrest Stanley Chapman. When Sergeant Moss asks him about promising to let Freddie leave, Campbell states that the promise means nothing to him. He says that his campaign against the Peaky Blinders has become personal .
Polly is waiting for him when Freddie goes to visit his mother's grave. Polly warns Freddie about the deal Thomas made with Inspector Campbell, and Freddie tells her that Stanley Chapman does not know Freddie’s address, and that the police will keep beating him for it. Freddie refuses to leave Birmingham.
Sergeant Moss shows Campbell a dead Stanley Chapman, who had a seizure after being whipped repeatedly. Sergeant Moss is clearly disturbed by Campbell’s way of handling things.
Billy Kimber visits the Shelby Home and hands Thomas a legal betting license; the Shelby family’s first legal racetrack pitch.
Grace Burgess helps Arthur Shelby with his calculations. She discovers that the Shelby family contraband always stay near petrol boat moorings, and that the boats are moored at junctions. She gives the information to Campbell, who searches them for the stolen guns, but comes up with nothing but cigarettes and whiskey.
After hearing about how Grace was asking questions about how they run their business, Thomas brings Grace to the Catholic Church. He discovers that she is not a Catholic at all—this being the second time she has lied to him. Thomas tells Grace that he wants her to work for the Shelby family as an assistant (similar to what Roberts does for Kimber), and he kisses her.
Thomas offers Lizzie Stark eight pounds for her to service him one last time before she marries his brother John. Lizzie accepts the money, and Thomas tells her to keep it, and that he was just testing her. He tells Lizzie that he will tell John the truth.
Campbell and Grace meet again and update each other. He didn't find each anything at the warehouses, and Thomas has asked her to be his bookkeeper and secretary. Campbell notes that Thomas has fallen quite heavily for her.
Thomas tells John that he offered Lizzie money to service him and that she said yes. John decides not to go see Lizzie like he had planned.
Thomas gives Grace her first job: to see Ada at Montague Street and bring her an invitation to a family occasion, and to tell her there will be a truce. John breaks into Thomas’s room and uses his pipe to smoke opium. He tells Thomas that he found out that Lizzie still sees a couple of regular customers.
The next day, the Shelby brothers go to settle the war with the Lees. But when they arrive Thomas reveals to John that they will not be fighting, instead he will be getting married to a Lee family member to settle the dispute. John marries Esme Lee, and they have a wedding with fireworks and dancing.
Ada’s water breaks at the wedding. She gives birth to a baby boy, and Thomas allows Freddie to come see his son.
Grace tells Inspector Campbell of Freddie’s location, and the police come and take Freddie away. Ada, and the rest of the Shelbys believe that it was Thomas who turned Freddie over to the police, and as a result, Polly yells at Thomas, calling him a liar.
- Ada is the one to tell Polly about the money that Stanley Chapman is holding.
- Thomas had been employing Lizzie's services for the last two years, but Lizzie never told John.
- When they were kids, Thomas used to do voice imitations.
- Esme Lee's dad gives John a car as a dowry.
- John Shelby (to Thomas Shelby): “Right, I want it known, if anyone calls her a whore again, I will push the barrel of my revolver down their throats and blow the word back down into their hearts.”
- Polly Shelby: “Men and their cocks never cease to amaze me. John, Lizzie Stark’s never done a day’s work vertical.”
- Polly Shelby (to John Shelby): “Brave is going where no man’s gone before. And with Lizzie Stark, John, that is really not what you’ll be doing.”
- Johnny Dogs (to Thomas Shelby): “I got you ten minutes with her. You can at least say thank you, it’s easier to see the Pope these days.”
- Grace Shelby: “I’m not an accountant nor a lawyer.”
- Thomas Shelby: “No, but you have something I need. Class.”
- Lizzie Stark: “Your brother is ten times the man you are.”
- Thomas Shelby (to himself): “Of that, I have no doubt.”
- Thomas Shelby: “Can you make a toast?”
- Grace Shelby: “I’m Irish, I can make a million toasts. May you be in heaven a full half hour before the devil knows you’re dead.”
- John Shelby: “You must think I’m an idiot.”
- Thomas Shelby: “I think you’re the first Shelby to have a legal betting license for anything. What would our granddad say, eh? He’d be turning in his grave. ‘Honest bloody money? Eh? In this house? Here?’”
- Thomas Shelby: “Listen, I have already betrothed you. So if you back out now there’s going to be one fucking mighty war breaking out here that’s going to make the Somme—It’s going to make the Somme look like a fucking tea party.”
- Thomas Shelby (to Polly Shelby): “You’re right, Pol. Freddie should be here.”
- Polly Shelby: “Is that a heartbeat I hear inside that chest?”