Clawdeen Wolf plans a 'Flashion Mob', a surprise fashion show starring herself and her friends at school. Meanwhile, Rochelle Goyle chases after a rose petal given to her by Garrott du Roque, her boyfriend from Scaris, which was knocked from her hand by students attracted by the attention from Clawdeen's show. However, thanks to a 'mix-up' from Toralei, Heath is put in a dress and heels and ends up clumsily tripping and abruptly ending the show.
Thanks to Ghoulia, however, the fashion show was put on FrightTube (with the awkward ending edited out) and had gotten quite a large amount of views, including Moanatella Ghostier, a renowned fashion designer. Clawdeen urges Ghoulia to remove the video, as fashion is about rules and Clawdeen herself believes she broke most of them with her outfits. But it had already caught Moanatella's attention, who had a very unique problem. She needed a protégé to carry on her designs, as she was running out of ideas and when people stop paying attention to her, she fades away. So she sends for three students, Jinafire Long from Fanghai, Skelita Calaveras from Hexico and last but not least, Clawdeen Wolf. Bloodgood calls in Clawdeen and her friends to explain the good news, and with a little begging, agreed to let her friends, consisting of Frankie Stein, Draculaura, Abbey Bominable, Cleo de Nile, Ghoulia Yelps and Lagoona Blue. She also let Rochelle Goyle accompany them, as she is from Scaris.
On the plane, Rochelle tells Frankie about Garrott, and how he had bred his own special rosebush just for her so she would know how special she was to him. However, she also explained that he had stopped writing letters to her some time ago, and she concluded he had met someone else. Frankie refuses to believe this and decides that, whilst in Scaris, she would take Rochelle to find Garrott and get an explanation. Also revealed is that Toralei stowed away on the plane, hitching a ride to Scaris.
Finally in Scaris, the ghouls drop Clawdeen off at Moanatella's headquarters, and Frankie, Rochelle, and Ghoulia Yelps go look for Garrott in secret while the remainder of the group take in the sights. Clawdeen meets Jinafire Long and Skelita Calaveras and though friendly with each other, Moanatella coldly reminds them that only one of them will be her apprentice. With Ghoulia's scooter, the chase for Garrott begins elsewhere when they spot someone else on a scooter with a jacket akin to Garrott's. The chase takes them into the catacombs of Scaris, and when prompted upon a certain passageway, Rochelle urges them to take a different route as it is said that monsters who go through there don't come out. Unfortunately the chase is a bust, as the rider was only Catrine DeMew and Ghoulia crashes and breaks her scooter beyond repair.
Meanwhile, in the cafe, Cleo, Abbey, Draculaura, Lagoona and Toralei talk about frightseeing only to see Ghoulia very sad about her scooter. Ghoulia says it's worth about a jillion and sees an idea on how to get money nearby.
Somewhere, in Moanatella Ghostier's Headquarters, Skelita and Clawdeen talk about Skelita's tribute to her family. Clawdeen notices Jinafire's book around and decides to see her designs, but Jinafire becomes angry and scolds Clawdeen about the competition and that they're not supposed to be helping each other. Back in Monster High, Clawd Wolf (who becomes mega jealous of Draculaura, being in the most romantic city in the whole world without him - thanks to Heath Burns) seeks help from C.A. Cupid, and misunderstands her advice. He flies to Scaris with Deuce Gorgon (who misses Cleo a lot) and Heath, even when he told him not to go.
Back in the headquarters, Clawdeen was shouted at by Moanatella for the third time for not following the rules of fashion. Later on, she finds courage to look for inspiration on her old sketch book but Moanatella comes and tells her to throw it away, so she does after Moanatella goes through the floor. So, she starts designing like her the same time Toralei seems to make the frightseeing less fun for the other ghouls. After that, Moanatella tells the three designers that if they hear her ring the bell for three times, it meant she made a decision. She leaves after saying this.
In the cafe, Frankie and Rochelle discuss about Garrett and seems to find a clue as to where he was. The scene shifts to Jinafire and Skelita finding Clawdeen's book and sees it. Clawdeen walks in, and tells them to stop looking because she already improved. But, Jinafire and Skelita tells her that she wasn't being original already and that seeing her now saddens them.
Back to Frankie and Rochelle, they are now in the Catacombs of Scaris, where they are lead by vines of the special rose bush to the forbidden area where it is said that no monster who came in ever came out alive. They find Garrett who has been used by Moanatella for his fashion designs. This was why he couldn't write to Rochelle anymore. He tells them whoever wins Moanatella's "apprenticeship" will be locked up in the same place and be used just like him. At that moment, Moanatella and Clawdeen enter, and Moanatella traps Clawdeen in a cell with Garrott, Frankie and Rochelle.
Clawd, Deuce and Heath wander the streets of Scaris (passing by Ghoulia without noticing her) looking for the ghouls. Clawd smells Clawdeen's scent and follows them into the catacombs. Using their powers, they rescue the ghouls and Garrott. Clawdeen announces a desire to 'beat Moanatella at her own game.' Skelita and Jinafire show up, having sensed that something bad was going to happen, and give Clawdeen her old design book back. The rest of the ghouls get to work designing a full fashion line of clothing, while Moanatella sets up her own fashion show across town.
Despite having lots of help, the ghouls aren't going to get finished it time, so Clawd reveals that it's a full moon, which causes Clawdeen to work double-time. At last, the show is finished, so they gather it up to take it to the fashion show. Ghoulia (who has bought a car with the money she's earned!) offers to help them get to the show.
They crash Moanatella's show and show off Clawdeen's real fashion line. The people love it and cheer Clawdeen, causing Moanatella to vanish forever because no one is paying attention to her. Skelita and Jinafire express a desire to transfer to Monster High, while Garrott tells Rochelle that he will stay in Scaris. The movie ends with the Monster High group posing at the fashion show.
- The title City of Frights is a pun on "City of Lights", the most popular nickname of Paris. It is a rough translation of "La Ville-Lumière", and it owes the nickname firstly to it being the centre of education and ideas during the Age of Enlightenment and later to its early adoption of street lighting.
- The tourist group discusses a few places they can go see. These are the Eiffel Terror, a reference to the Eiffel Tower, Ogre Dame Cathedral, a reference to Notre Dame Cathedral, and the Boovre, a reference to the Louvre.
- The skeletons next to the entrance to the forbidden portion of the Catacombs of Paris are positioned as the three wise monkeys.
- The Monster High rendition of the Venus de Milo bears a similarity to C.A. Cupid, the adopted daughter of Eros, Venus's (Aphrodite's) son and/or servant.
- The hunchbacked fashion model named Modo is a reference to the main character from Victor Hugo's 1831 novel: The Hunchback of Notre-Dame.
- Rochelle became hall inspector in the Volume 3 webisode "The Halls Have Eyes".
- Skull Shores is the island that was the location of most of the events in "Escape From Skull Shores".
- Ghoulia acquired her scooter in the Volume 3 webisode "The Need for Speed".
- The Valentine-reference of Heath and Clawd's subsequent idea to talk to C.A. recall the events of "Why Do Ghouls Fall in Love?".
- Moanatella Ghostier, Garrott du Roque, Catrine DeMew, Skelita Calaveras, and Jinafire Long make their cartoon debuts.
- The café cart and convertible make their cartoon debuts.
- During the fashion show at Monster High, rather than her fashion pack shoes, Abbey wears her Skull Shores shoes. While an error in the sense that the animation does not properly depict the doll product, this was likely done intentionally because Abbey's fashion pack shoes are the same model as Clawdeen's School Clubs shoes, which Clawdeen already wears during the same fashion show.
- Jinafire's sword-belt, which she makes when she meets Clawdeen, disappears by the time the girls are led to the atelier.
- In most European countries, including France, one has to be at least eighteen years of age to drive a car. This law also applies to citizens of the USA regardless whether they already acquired their license at either seventeen or sixteen.
- While law and common use in the USA, Europe isn't too big on bicycle helmets. If it's for transport or casual recreation, bicycle helmets are generally not worn in France. The French cyclists with helmet are therefore an unlikely sight that reflects USAmerican culture more than French.
- A lot of fashion is featured in Scaris: City of Frights. They are: Clawdeen's School Clubs outfit, Toralei's and Cleo's 'Maul Session' outfits, Abbey's, Lagoona's, and Draculaura's new fashion packs, Frankie's new fashion pack, an unknown outfit for Venus, the entire Scaris: City of Frights fashion line, and catwalk outfits for Clawdeen, Cleo, Frankie, Abbey, Lagoona, Draculaura, Deuce, Clawd, and Heath. The shoes Draculaura picks out of her closet are her Skull Shores shoes.
- The Venus de Milo statue is a mix of C.A. Cupid's regular head model and a lightly modified version of Draculaura's Skull Shores body model.