The plot concerns the disappearance of the fiancé of Johanna Oakley in the midst of the mysterious disappearances of customers who pay a visit to the shop of the peculiar barber by the name of Sweeney Todd. Meanwhile, the business of the pie shop owner Mrs. Lovett has been a success. As time goes on and an investigation is launched, everything falls into place as the people of London are revealed the terrible truth.
Despite its reputation as a penny dreadful, its success derives from the shocking themes and the gut reaction of the readers, playing off the people's worst fears of murder and cannibalism.
This is the original story of the infamous Demon Barber, which would receive a number of adaptations in both stage play and film, before a new stage play by Christopher Bond, based off the original but with an entirely new story, would capture the imagination and be adapted into a musical that would also be later adapted into a Tim Burton film. Also was adapted into a Hidden Object Game.
Tropes featured in the penny dreadful are:
- Ambiguous Situation: Sweeney claims to a disguised Johanna that he used to be a poor orphan. Because it wasn't elaborated on, though, it's hard to tell whether it could be a legit Dark and Troubled Past or Blatant Lies.
- Arranged Marriage: What Mrs. Oakley tried to do with Johanna as part of her bargain with Reverend Lupin for salvation.
- Bedlam House: Fogg Asylum is a hellhole for anyone sent there. Tobias is placed there against his will by Sweeney himself.
- Bittersweet Ending: Sweeney Todd is caught and executed for his crimes, Mark and Johanna are reunited and married, and Fogg's Asylum is taken down. However, some hundreds of victims were killed and made into Mrs. Lovett's pies, and the poor citizens who used to frequent her shop will never look at pies the same again...
- Calling the Old Man Out: Johanna calls out her mother's attempts to marry her to Mr. Lupin in return for salvation, citing the hypocrisy of the reverend.Johanna: "Mother...if you are so far gone in superstition as to believe this miserable drunkard ought to come between you and heaven, I am not so lost as not to be able to reject the offer with more scorn and contempt than I ever thought I could have entertained for any human being."
- Cassandra Truth: Tobias told his mother of the true nature of Sweeney Todd. She doesn't believe him.
- Cut His Heart Out with a Spoon: Sweeney's threat to a disguised Johanna: "By all that's furious, I'll tear out your teeth with red-hot pincers, and scoop your eyes from their gory sockets with an old oyster knife. Damn you, I'll—I'll flay you!"
- Daddy's Girl: Johanna has the full parental love and support of her father.
- Dangerously Close Shave: How Sweeney Todd finishes off his victims should they survive the fall from the trap door.
- Distressed Dude: Mark Ingestrie fell victim to this when Mrs. Lovett forced him to bake her meat pies.
- Disguised in Drag: Johanna disguises herself as a boy in order to enter Sweeney's shop.
- Earn Your Happy Ending: After all the hell Mark had to endure enslaved in the pie shop and the risk Johanna took to investigate the barber shop after avoiding an unwanted marriage with the reverend, they are finally reunited and are later Happily Married.
- Evil-Detecting Dog: The dog of the missing Thornhill senses something sinister about Sweeney and his shop. Then the dog goes missing.
- Early-Installment Weirdness: Sweeney Todd is completely unsympathetic and motivated by greed in the original book while later installments give him redeeming qualities and change his motivations to either revenge or jealousy. Sweeney also mostly kills using a trapdoor, using the iconic razor only if his victims survive the fall.
- I Am a Humanitarian: Not perpetrated by Sweeney and Mrs. Lovett themselves, but they do secretly distribute meat pies made of human flesh to unaware customers in the pie shop.
- I Ate WHAT?!: Taken to a horrifying level when Mrs. Lovett's customers finally realize that the meat pies are made of human flesh all along.
- Implied Death Threat: Sweeney threatens to cut Tobias's throat if he ever saw or heard anything that happens in his shop. He didn't follow through with it, but...
- Oh, Crap!: When Sweeney discovers Sir Richard alive, having figured out a way to survive the trap, he is terrified.
- Prior to this, Tobias thinks this when he discovers what Sweeney has been hiding.
- Payment Plan Pitch: Sweeney advertises his barber shop as follows - Easy shaving for a penny, as good as you will find any.
- Poison Is Evil: How Mrs. Lovett meets her demise.
- Posthumous Character: Thornhill, the deliverer of the string of pearls, is never seen, yet his disappearance is what sparks suspicions to Sweeney.
- Public Execution: Sweeney Todd's fate.
- The Reveal: Mark tells the horrid truth to Mrs. Lovett's customers with this line.Mark: "Ladies and Gentlemen - I fear that what I am going to say will spoil your appetites; but the truth is beautiful at all times, and I have to state that Mrs. Lovett's pies are made of human flesh!"
- The Secret of Long Pork Pies: Mrs. Lovett helps dispose of Sweeney's victims by baking them into her signature meat pies and distributing them to her customers.
- Trap Door: How Sweeney deals with most of his victims. However, should they survive the fall...
- You Have Outlived Your Usefulness: Seeing no need to keep her alive, Todd gets rid of Mrs. Lovett with poisoned wine without her knowing it was until it was too late.
- Todd and Mrs. Lovett had plans to kill Mark and make him part of the meat pies once his usefulness has reached its end. Fortunately, she doesn't get the chance.
