It is 1919 in Birmingham where Thomas Shelby a war veteran is head of a feared gang called the Peaky Blinders. They make living from illegal betting, protection and the black market. After he gets his hands on a crate of guns from the local arms factory, he sees an opportunity to increase the gang's power and move up in the world.
At a country fair just outside of Birmingham, Thomas Shelby is involved in a unhappy fight with a gypsy family called the Lees. Chief Inspector Campbell conducts a unhappy raid on the Peaky Blinders' territory, leaving a message with Aunt Polly that he wants to speak directly to Thomas. Thomas agrees to meet with him but preferring not to take part in talks whilst on the back foot, he decides to strike a blow back first. The Lee family declare war on the Peaky Blinders.
The tension between The Peaky Blinders' and the Lee family continues to increase. After the Lee family ransack the Shelbys' betting shop, Thomas decides to go visit them himself. Thomas's brother John is a widower with four children who have been running rings around him, reveals that he intends to remarry. Chief Inspector Campbell puts more pressure on Thomas to deliver him Freddie Thorne and the stolen guns.
Thomas Shelby's war with the Lee family of gypsies escalates, and Campbell puts further pressure on him to deliver the stolen guns. Meanwhile Thomas's brother John plans to marry a former prostitute, but Thomas suspects that she's still on the game.
Inspector Campbell is still looking for the crate of stolen guns. Thomas Shelby's life is complicated are two individuals show up in town. The first is the Shelbys' errant father, who walked out on the family around ten years ago. He is now claiming that he has completely changed. The other is a man from South Armagh who has learned about the guns. Grace makes a discovery that could end up changing everything.
The Worcester races are taking place and it is the day Thomas intends to finally become a racecourse kingpin. The Peaky Blinders are about to make their move but some revelations are revealed that threaten to ruin their plans. Grace has to try and make an impossible decision whilst Inspector Campbell plays his last card.