1775. On the anniversary of a long-ago murder, a mysterious stranger stops at the Maypole Tavern. Later, an injured man, Edward Chester, is found on the road by Barnaby Rudge, a mentally ill young man, and Gabriel Varden, a locksmith.
Mr. Chester visits his son at Mrs. Rudge's house, and discovers his romance with Emma Haredale, a young Catholic lady. Simon, Varden's apprentice, sneaks out at night.
Simon attends a meeting of dissident apprentices. Joe Willett rides into London, taking a letter from Emma to Edward. Chester arrives at The Maypole and sends a note to Mr. Haredale via Barnaby.
Chester and Haredale agree to separate Emma and Edward. Haredale returns home to find them together, and forbids Edward the house. Chester tells his son that he must marry for money. The Stranger reveals himself to Mary Rudge.
The Varden family visits The Maypole; Dolly calls on Emma, delivering a note from Edward and receiving her reply. Hugh, the hostler, accosts Dolly, steals Emma's letter, and takes it to Chester.
Chester convinces Mrs. Varden to discourage Edward and Emma. Hugh intercepts another letter. Varden and Haredale visit Mary's house and find her and Barnaby gone.
The Stranger seeks shelter with Stagg. Joe joins the army. Edward and Chester quarrel. Next scene: The Maypole, two years later. Solomon Daisy enters, and says he's seen a ghost. Anti-Catholic agitator Lord George Gordon arrives.
Gordon and Gashford plan a mass demonstration in London. Willett, with Hugh as a bodyguard, goes to tell Haredale about the ghost. Stagg arrives at Mary's remote cottage, and threatens her. Hugh joins Gordon's group.
Hugh visits Chester, who suggests revenge on Haredale, and then meets Simon and Dennis the hangman at The Boot, a disreputable inn. Mary and Barnaby travel to London. Haredale is attacked by the Gordonites, but escapes.
Mary and Barnaby are separated in London. Barnaby finds Hugh, and joins the demonstrators. The protest turns into a riot, spurred by Gashford; Catholic chapels and properties are looted and burned.
The rioters loot The Maypole, but Hugh saves Mr. Willett; they go on to attack Haredale's home. Willett sees a ghost. Haredale finds his house burned and Emma and Dolly missing; he seizes Rudge in the ruins. Barnaby is jailed.
The rioters try to force Varden to open all the prison locks. Barnaby meets his father in jail. Varden is rescued by Edward and Joe Willett. The mob burns down Newgate and the prisoners are freed. The King deploys troops.
Edward and Joe rescue Emma and Dolly. Barnaby and Hugh are caught and condemned to hang. Varden discovers the secret of Hugh's birth, and strives desperately to save them. Haredale and Chester duel to the death.