A chilling chorus sets the scene in 1846 London, where a factory whistle screams and the citizens beckon the audience to witness a tale of blood and vengeance

Sweeney Todd, once known as Benjamin Barker, returns to London with a young sailor, Anthony Hope, who saved him at sea. Sweeney reveals he was falsely exiled by the corrupt Judge Turpin, who coveted his wife, Lucy. On Fleet Street, Sweeney visits Mrs. Lovett’s pie shop, where she tells him Lucy was raped by the Judge and later poisoned herself. Their daughter, Johanna, is now the Judge’s ward. Mrs. Lovett, recognizing Sweeney’s true identity, returns his barber razors. He vows revenge.

Meanwhile, Anthony glimpses Johanna in a window and falls in love. He tries to connect with her, but the Judge and his enforcer, the Beadle, keep him away. Sweeney reestablishes himself as a barber by besting a flamboyant rival, Pirelli, in a public shaving contest. When Pirelli later threatens to expose Sweeney’s identity, Sweeney kills him.

Judge Turpin, obsessed with Johanna and planning to marry her, agrees to a shave at Sweeney’s shop. Sweeney prepares to kill him but is interrupted by Anthony, who blurts out his plan to elope with Johanna. The Judge storms off. Furious, Sweeney snaps. He declares no one is safe from his blade. Mrs. Lovett suggests using his victims in her meat pies. The two form a gruesome partnership.

As business booms, Anthony discovers Johanna has been locked in an asylum. Sweeney helps him pose as a wigmaker to infiltrate it. Meanwhile, Mrs. Lovett, now guardian to Pirelli’s assistant Toby, tries to keep the boy from discovering their secret. But Toby grows suspicious and is eventually locked in the bake house cellar.

Johanna kills the asylum director during her escape. Anthony brings her to Sweeney’s shop and hides her while he fetches transport. In the chaos, the Beggar Woman reappears, warning of danger. Sweeney, not recognizing her as his wife, Lucy, kills her to silence her.

When the Judge returns, Sweeney reveals his true identity as Benjamin Barker before slitting his throat. Johanna narrowly escapes the same fate. In the bake house, Sweeney realizes the Beggar Woman was Lucy all along. Enraged at Mrs. Lovett’s deception—she knew Lucy lived but said she was dead—he kills her by throwing her into the oven.

Sweeney mourns Lucy’s body until Toby, traumatized and white-haired, appears behind him and slits his throat.

In the epilogue, the chorus warns that the thirst for revenge only leads to destruction. Sweeney rises, glares at the audience, and slams the oven door shut.