The three ghoulfriends, Robecca Steam, Venus McFlytrap, and Rochelle Goyle, are on the case to solve the mystery of the missing headmistress! First up is investigating the creeperiffic attic on the Monster High campus, where someone appears to have been hiding out amongst the lacy webs! Who is she, and what's her secret? The ghoulfriends soon find out and uncover a much bigger plot that puts the future of the entire student body in danger!
- The Three Monsketeers is a play on the 1844 novel The Three Musketeers.
- Got Bloodgood? is a play on the 1993 advertising campaign Got Milk?.
- "Goredashian" is a reference to Kardashian.
- "Alexander McScream" is a reference to Alexander McQueen.
- "Gill Baits" is a reference to Bill Gates.
- "Usain Thunderbolt" is a reference to Usain Bolt.
- Clawdeen is said to be the latest winner of the "Moanatella Ghostier Fashion Fellowship". This means events similar to "Scaris: City of Frights" happened in the Ghoulfriends continuity between the first and second semester.
- Captain Penny is identified as female twice late in Chapter 1. In truth, according to the doll logs diaries and Robecca's doll profile bio and website profile, Captain Penny is a male.
- While yellow teeth aren't generally a pleasant sight, it is peculiar for Draculaura to be horrified of having any yellow on her considering it's her principle secondary color.
- It is the first, only and last Ghoulfriends book to not start with the title Ghoulfriends, and instead is titled Who's That Ghoulfriend? It is also the first and only Ghoulfriends to not use the book series title as the book title as a "use same for both scenarios" kind of deal, as all other books of this series have, for example, the word "Ghoulfriends" printed at top and followed by the title "Forever" or say Ghoulfriends on top, and say just Just Want to Have Fun at the bottom.
- As in the previous two books, Coach Igor is mentioned, but has no role in the events of the book. Bloodgood's also only mentioned in this third book.