The cover shows Bim, an orange alien, holding a bag of candy.
On October 30th, brother and sister Chris and Meg Oliver rescue a young child in a costume stuck in a bush. But, they discover the "child" is really Bim, a smelly alien with a lot of disgusting habits. Bim promptly swears allegiance to them. On October 31, Bim's people invade Earth. The twins find their souvenir from HorrorLand maybe the only thing that can save or harm them! In the third part of the story, Meg returns to HorrorLand and is sent on a mysterious mission by Jonathan Chiller. Meg also spots another her running around. It turns out that the other Meg and Chris were robots and while Meg was tuggging at Chris's ears they fell of and Jonathan Chiller was sad because she broke the robot so she was sent home again.
Cover Art Gallery
- Bim's skin was originally green as seen in the full artwork. However, when the book was released, his skin was changed to orange. The book was later re-released with alternative cover art where Bim's skin is green, and his eyes were changed from purple to orange. A "SPECIAL EDITION" banner was also added underneath the Goosebumps HorrorLand logo.
- With 192 pages and over 34,000 words, this is the longest Goosebumps book ever. The book Goosebumps Wanted: The Haunted Mask is 240 pages long, but it has a lower word count than Weirdo Halloween.