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Attack of the Mutant is the twenty-fifth book in the original Goosebumps book series. It was first published in 1994.

The cover illustration shows the Masked Mutant outside of his headquarters.



Skipper Matthews has an awesome comic book collection. His favorite one is called The Masked Mutant. It's about an evil supervillain who's out to rule the universe! Skipper can't get enough of The Mutant. Until one day he gets lost in a strange part of town. And finds a building that looks exactly like The Mutant's secret headquarters. A building that appears and disappears. Has Skipper read one too many comic books? Or does The Masked Mutant really live in Riverview Falls?


Skipper Matthews loves comic books. His favorite series is The Masked Mutant, a comic series about a shapeshifting villain named the Masked Mutant. However, his father disapproves of his hobby, his bratty sister Mitzi mocks him for it, and his friend Wilson doesn't understand it. One day, Skipper has to go to the orthodontist. While riding the bus there, he meets a girl who introduces herself as Libby Zacks. After talking with her for a while, Skipper realizes that he has missed his stop. Skipper gets off the bus and sees a tall, pink building. The structure looks exactly like the Masked Mutant's headquarters. However, Skipper doesn't want to be late for his appointment, so he doesn't have time to investigate.

Skipper doesn't get a chance to go back to the building until a week later. He rides the bus to the same spot as last time, but he discovers that the building has seemingly vanished, leaving only an empty lot. Skipper eventually goes home, and he's been delivered another entry of The Masked Mutant. In the story, the Masked Mutant disguises his headquarters with an invisibility curtain. Skipper deduces that the building from early must have been disguised in a similar way.

Skipper eventually gets back on the bus. He meets Libby and tries to explain his theory. Libby is skeptical, but she agrees to investigate the seemingly empty lot with Skipper. As the kids walk farther into the lot, the building appears before them. Skipper sneaks inside the building, and Libby reluctantly follows. A yellow light shoots out of a wall and onto Skipper, but he can't discern what it was supposed to do. The two kids enter an elevator. The elevator unexpectedly takes the kids down. When the doors open, the kids are greeted with what appears to be a basement. None of the elevator's buttons seem to do anything, so they are forced to get out. As Skipper is walking, he notices that he's become separated from Libby. Skipper finds a room filled with drawings for The Masked Mutant, and he begins to suspect that he's in the production headquarters for the series. However, Skipper's excitement is cut short when he finds sketches of himself. Libby finds Skipper, and she convinces him to leave.

Skipper makes it home, and he's received another issue of The Masked Mutant. The comic declares that the titular villain has a new foe. The story depicts Skipper sneaking into the Masked Mutant's headquarters to save the Galloping Gazelle, a hero in the series. Skipper ends up heading back to the headquarters, suspecting that the Galloping Gazelle really is in danger. Inside, Skipper enters an elevator, and it takes him up to the top floor without being prompted. There, Skipper find The Galloping Gazelle, who has been tied to a chair. Skipper unties the hero, and the two leave in search of the Masked Mutant.

The duo finds the Masked Mutant, and the Galloping Gazelle runs around him, attempting to use his super-speed to cause a whirlwind. The Masked Mutant easily trips the hero. The Mutant turns into a leopard, and the Galloping Gazelle runs away, leaving Skipper on his own with the villain. The Masked Mutant wants to know what Skipper's superpowers are, but Skipper insists that he doesn't have any. The villain lifts Skipper into the air, but Libby enters the room. The Masked Mutant tells Libby that she isn't allowed to leave. Libby pulls out a toy gun and aims it at the villain. She insists that — if they're in a comic — they can do anything that they want. She pulls the trigger, and the gun shoots out a beam, dissolving the evil-doer. Skipper is initially happy, but he watches Libby transform into the Masked Mutant. The Masked Mutant reveals that the villain who was disintegrated was the Magnificent Molecule Man, who was filling in for the Mutant. As Skipper slowly learns that Libby was never real. The Mutant explains that he wants new foes, and — because Skipper is knowledgeable about the series — he would make a great character. The light that had shone on Skipper when he first entered the headquarters turned him into a comic book character.

Skipper gets an idea. He declares that he is actually the Colossal Elastic Boy, and he can only be defeated by sulphuric acid. The Mutant turns himself into a wave of acid, which Skipper dodges. Skipper knows that he has defeated the villain because the Mutant can only turn into solids; if he turns into a liquid, he's trapped in that form.

Gleefully, Skipper goes home, and he decides to cut some cake for him and Mitzi. While doing this, Skipper accidentally cuts his hand with the knife, but blood does not come out of the cut. Instead, he bleeds ink. He asks Mitzi to get her the new comic that came in, as he suspects his career in comics isn't over yet.

Reprints and rereleases

Book Release date Type Media

2003 - 2007 reprint series

March 2004 Standalone Paperback

International releases

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  • In the UK, this is the twenty-third book in the original series.
  • In Portugal, this is the twenty-ninth book in the original Goosebumps series.
  • In the Portuguese adaptation of the story there are some notable differences:
    • Skipper Matthews is called "Saltitão Borges."
    • Libby is called "Lili."
  • In France, this is the fifteenth book in the original series.
    • Skipper Matthews is called "Jim."



TV series

Attack of the Mutant was adapted into a two-part episode of the Goosebumps TV series. It is the second (part one) and third (part two) episode of season two, and the twenty-first and twenty-second episode overall.


Audiobook Release date Length Narrated by Published by
November 1996 60 minutes Richard Horvitz Walt Disney Records

Video game

Main article: Attack of the Mutant (video game)

Attack of the Mutant was adapted into a first-person video game by DreamWorks Interactive, released for PC on May 1, 1997.



  • R.L. Stine claims that this book has the best surprise ending of all Goosebumps books.
  • According to the original book, the Masked Mutant has had 26 comics before he was killed by Skipper. (24 comics before he escaped into the real world and 2 comics after he escapes.)
  • This book only mentions three members of The League of Good Guys: The Amazing Tornado-man, The Galloping Gazelle, and SpongeLife (a.k.a. The Sponge of Steel). According to the Goosebumps Official Collector's Caps Book, The League of Good Guys consists of six members, and the others are: Rott Weiler — The Human Guard Dog, Clara the Claw Woman, and The Fantastic Ferret.
  • The 1996 audiobook adaptation features voice work from voice actors Richard Horvitz and Townsend Coleman.
  • This book references Jack Kirby's Captain America and Todd McFarlane's Spawn. Libby reads High School Harry and Beanhead, a parody of Archie and Jughead. Skipper says that the creator of the Masked Mutant comics is Jimmy Starenko, a reference to Jim Steranko. The Galloping Gazelle has super powers similar to The Flash. Elastic Boy has super powers similar to Plastic Man and Mr. Fantastic. The League of Good Guys is similar to the Justice League. Additionally, the book references Frosted Flakes and Pop-Tarts.
  • The 2018 ebook changes Skipper mentioning shoes that "pump up or flash lights when you walk in them" to "The ones that light up when you walk in them".
    • A mention of a bus token is changed to just "money".
    • "My eye caught something on the shelf." is changed "Something on the shelf caught my eye"

References in other Goosebumps media