The series takes place in early 20th-century England and follows a criminal family and the numerous challenges faced by its leader, Tommy Shelby, in the underworld.
In season 3, Tommy Shelby finally gets married, and his family finds themselves in danger from a mysterious guest, while Tommy becomes involved in more dangerous situations than he was used to before.
Having clashed and parted ways a year earlier, the Shelbys are forced to join forces and enlist the help of a suspicious ally as they find themselves involved in a Mafia feud.
Set against the backdrop of the Wall Street Crash of 1929; Tommy faces unexpected troubles, while young family members and foes pose new threats.