Birmingham, 1919. Thomas Shelby controls the Peaky Blinders, one of the city's most feared criminal organisations, but his ambitions go beyond running the streets. When a crate of guns goes missing, Thomas recognises an opportunity to move up in the world.

Thomas Shelby plans to go to Cheltenham races in order to get closer to Billy Kimber. Knowing the gangster's appetite for beautiful women, Thomas invites Grace to accompany him. Meanwhile some IRA sympathisers approach Thomas with an offer to buy the stolen guns.

As Thomas Shelby prepares to oust Billy Kimber, hidden secrets are revealed and the family have to face up to the problems that have divided them. Meanwhile, Campbell, obsessed with taking down the Peaky Blinders, unleashes one last plan to destroy them.