The Goosebumps book where a shapeshifting supervillain turns out to be real.
Bradley "Skipper" Matthews collects comic books, but doesn't read them. With one exception: The Masked Mutant. One day, Skipper misses his bus stop and discovers a building that resembles the Masked Mutant's HQ. Things get weirder when he and his new friend Libby explore the building and the events in the comics begin to reflect what's happening in real life. Is Skipper losing his mind, or is there something much more sinister going on?
It was adapted into the second and third episodes of the second season of the 1995 TV series, with a novelization based on the episode being released as book 12 of the Goosebumps Presents series. It was also adapted into the 1997 PC game Attack of the Mutant, which had a different plot from the book and episode.
The book provides examples of:
- Ambiguous Situation: It turns out that Libby was actually the Mutant in disguise all along. But this doesn't reveal if there ever was a real Libby who was impersonated by the Mutant, or Libby was just made up by him. However, considering that "Libby" had a house off of the lair that she brought Skipper to in order to show off her comic collection, it just might be the former.
- And the Adventure Continues: Implied by the end of the story; Skipper bleeds ink, as the Masked Mutant warned him what would happen after the laser hit him. After a moment's panic, he takes a deep breath and asks his little sister to pass him the comic book that just came in the mail, figuring that he may as well know what his next story is.
- Animal Motifs: Skipper's father reminds him of a big bear. Not only because he growls a lot, but also because he is big and broad. He has short, black hair and almost no forehead. And he has a big, booming roar of a voice, like a bear's roar.
- Bad Boss: The Masked Mutant, who disintegrates one of his top henchmen For the Evulz.
- Blatant Lies: When visiting the same bus stop where the Mutant lair was, Skipper is disappointed to find that it seemingly vanished. Libby, who initially greeted him when he arrived, indignantly asked him if he only came here just to look for the Mutant instead of hanging out with her. Skipper lies by denying this, and has to feign interest in her comics that she has at her house.
- Body Horror: The Masked Mutant's ability to "rearrange his molecules" and transform himself can look pretty ugly at times.
- Change the Uncomfortable Subject: When trying to tell his mother about the building that he's seen, which looks like the Masked Mutant's headquarters, she interrupts Skipper and says that she wishes that he was as interested in his homework as he is interested in his dumb comic books, and then asks him when was the last time that he read a good book. Not wanting to continue this conversation, which he has had multiple times before, Skipper then says that he dissected a worm in science class today. This actually disgusts her.Skipper: (narrating) There was just no pleasing Mom today.
- Dirty Coward: After a minor setback during his fight with the decoy Masked Mutant, the Galloping Gazelle simply flees, leaving Skipper at the supervillain's mercy.
- The Dog Was the Mastermind: Skipper's new friend Libby, who is actually the eponymous villain in disguise.
- Evil Is Hammy: The Masked Mutant, especially in the TV show.
- Explaining Your Power to the Enemy: Played with in the climax, when main protagonist Skipper Matthews is facing villain "The Masked Mutant", but then claims that he's not a normal human — he's actually a superhero, the "Colossal Elastic Boy", and quite happily explains the only thing that can destroy him — sulfuric acid. The Masked Mutant quickly thanks him for revealing this, and prepares to kill him. The catch? Skipper was lying, or so he thinks. His real motive was to take advantage of a weakness in the Masked Mutant's own powers — the Mutant can rearrange his molecules and become anything solid. Skipper changed him into becoming a liquid, which he can't turn back from.
- Fantasy-Forbidding Father: Skipper's dad really doesn't approve of his comic-collecting hobby and would rather he focus on keeping his grades up. He keeps threatening to throw out the whole collection, but never goes through with it.
- The Fourth Wall Will Not Protect You: Turns out the comic heroes and villains aren't so fictional after all.
- Greater-Scope Villain: Jimmy Steranko, The Masked Mutant's comic creator... possibly. For all we know, he's just another of the Masked Mutant's personas.
- Happy Dance: After getting rid of the Mutant once and for all, Skipper does a little dance on the carpet in which the Mutant melted on.
- Hoist by His Own Petard: The Masked Mutant's shapeshifting abilities doom him when Skipper tricks him into turning into a liquid, which he cannot revert from. See Tricking the Shapeshifter.
- I'm Melting!: Skipper manages to trick the Mutant into doing this trope himself by shapeshifting into sulfuric acid - whch he cannot change back from. He's then left to simmer on a carpet that he landed on.
- Invincible Villain: No one is able to defeat him, because he's too powerful and too clever.
- Invisibility Cloak: The Mutant's HQ employs one both in the comics and in real life, and you have to step through it to see the building. Despite this, Skipper still thinks it might be just an office building after all.
- Jerkass: Libby is pretty sardonic most of the time. She's even worse in her true form: the Masked Mutant.
- Kid Hero: Skipper, who works to find and stop the villainous Masked Mutant.
- Malevolent Masked Men: Kind of inverted in with The Masked Mutant. He spends most of his book in the form of a twelve-year-old girl, and doesn't show his mask until his true nature is revealed.
- Medium Awareness: The Masked Mutant. He also uses this to lure Skipper into a trap, since the boy reads all his stories.
- Mind Your Step: When Skipper and the Galloping Gazelle are going through the Mutant Headquarters, they come across a flight of stairs. The Gazelle advises Skipper to jump and not land on the first two steps, because there is a disintegrator-ray situated there. However, because Skipper is chubby, he lands on the first step. Luckily, nothing happens to him, to which the Gazelle surmises that the machine must be turned off.
- Onion Tears: Skipper's dad has these while helping prepare for dinner. This is why he doesn't pay attention to Skipper who's trying to show him a comic that has him featured in it, because he's too busy crying.
- O.O.C. Is Serious Business: After his adventure involving superheroes, Skipper runs home and offers Mitzi to play a game of frisbee with her. This causes her to gape at him in shock, as he usually never plays with her.
- Open Mouth, Insert Foot: When meeting Libby for the first time, she asks Skipper where he's going. Not wanting to say that he had an orthodontist appointment, he instead says that he is heading to a comic book store. But soon, he misses his stop, and then Libby asks a panicked Skipper if he wants to come over.Skipper: No. I'm late for my orthodontist appointment.
Libby: Huh? (narrows her eyes at him) You said you were going to a comic book store.
Skipper: (feels his face going red) Uh... I'm going to the comic book store after my appointment. - Pop-Cultured Badass: Skipper's in-depth knowledge of the Masked Mutant leads the Mutant to view him as the perfect opponent.
- Properly Paranoid: Skipper's dad warns that his comic book obsession will cause Skipper to be out-of-touch with reality. How right is he?
- Rhetorical Question Blunder: When catching Skipper reading comics instead of doing homework, his father angrily asks him if he knows why his grades are so bad. Skipper replies, "Because I'm not a very good student?" He then realizes that this was a mistake, because his father hates it when he answers back.
- Screw This, I'm Outta Here: When the Galloping Gazelle fails to defeat the Masked Mutant, he simply books it out of the Mutant's HQ, leaving Skipper at his mercy.
- Shout-Out:
- The comics that Libby likes, High School Harry & Beanhead, is one to the Archie comics. Skipper is not fond of them at all, as he thinks the art style is lame, and that the two main girls of the story are drawn exactly the same, only that one girl has blonde hair and the other girl has black hair. That the person who likes these comics is revealed to be a depraved supervillain in disguise might count as a Take That! as well.
- Additionally, the creator of the Masked Mutant comic book is the barely fictionalized Jimmy Steranko, an obvious reference to Jim Steranko- best known for his seminal work with Marvel Comics.
- The Stool Pigeon: Skipper Matthews' sister Mitzi, who likes to let his dad know when he's reading comics instead of doing his homework. According to Skipper, "Mitzi's hobby is being a snitch."
- Take Over the World: This is the goal of The Masked Mutant.
- Tentacled Terror: In the new issue of The Masked Mutant that Skipper gets at the start of the book, the Mutant changes into a monster octopus to try and squeeze the life out of one of his foes, SpongeLife. It doesn't work, because SpongeLife is able to squeeze himself small enough that he slips out of the Mutant's grip.
- Transforming Conforming: Near the end of the book, Skipper tricks the Masked Mutant by making him turn into Hollywood Acid. The Masked Mutant splashed into the carpet, making a big hole in it. The Masked Mutant can transform into anything solid and change back, but when he changes into a liquid he can't change back.
- Tricking the Shapeshifter: Skipper tells the Mutant that his only weakness is sulfuric acid, and the Mutant immediately transforms into just that. He remembers too late that he can only safely transform into solid objects, but once he turns into a liquid, he's stuck in that form.
- Understatement: When Skipper (who is quite chubby) is told to jump a bit far down a flight of stairs, he is hesitant to do so, saying, "I'm not very athletic."
- Worthy Opponent: The Masked Mutant considers Skipper this because he knows everything about him, and no other superhero was able to defeat him.
- "You!" Exclamation: The Mutant does this trope when he spots Libby entering his office. This was actually the real Mutant, and the fake Mutant was the Magnificent Molecule Man who probably recognized him for who "Libby" really was.
