"One Day at Horrorland" is a book in the Goosebumps series by R.L. Stine, first published in 1994, making it the 16th entry in the original series. (There have been, apparently, many different iterations of the Goosebumps series since its inception). Apparently, the characters and setting of "Horrorland", an amusement park that turns out to be supernaturally dangerous, became a popular fixture in the series.
Ooops, I just spoiled it, didn't I? Well, we could all probably guess what was happening. The characters should have, as well.
Lizzy Morris, her parents, and her bratty brother Luke and Luke's friend Clay are all out on a drive when they get lost and eventually end up at "Horrorland", a theme park staffed by workers in the costume of "horrors", horned green pig people. Since they were quite impatient after being lost, Lizzy ends up taking her brother and his friend around the park, on a series of increasingly unsafe rides. Despite repeatedly feeling endangered by the rides, they manage to convince themselves that it is all just part of the show. Until, after being reunited with her parents, they discover that the costumed "horrors" are in fact...not costumed at all! "Horrorland" is a theme park run by monsters, where they torment and (it is implied) kill people for their own amusement. Our family escapes, eventually, and the story has a somewhat happy ending.
The book did some things very well. Part of the book's realism is how it shifts from a real life stressful situation--- being stuck in a car with arguing parents and hyperactive children--- to a fantastic situation. And it maintains the tension throughout. Lizzy's attempts to communicate to her younger brother and his friend that they are in real danger, and that they should avoid distractions and find a way out, reminds me of real situations I have been in. And a big part of the feeling of menace in the story was how as long as Horrorland kept some of the trappings of a "theme park experience", the people inside of it kept trying to pretend that the danger wasn't real. It is a phenomenon that might occur in real life when people interact with medical or educational institutions, and fail to notice signs of abuse as long as appearances are maintained. So as far as this went, I feel the book managed to do a good job a horror story---within the content guidelines of Goosebumps' intended audience.
On the other hand, while some of the books in the Goosebumps series managed to actually build an atmospheric feeling of the eerie, as well as including themes of familiar dysfunction, this book felt more like an episodic adventure story, and at times almost seemed slapstick. Which was apparently part of what the series was about---mixing comedy and horror. And again, given the book's intended audience, it makes sense. And of course, as the commercial demands of the series became greater, the plots became a bit more formulaic. So while this has some good ideas and manages to create its own sense of tension, it doesn't quite do what other books in the series did.