The story follows four reprobates, in particular the clumsy and slow-witted Eddie who's pretty much scared of his own shadow, Hat (so-called because he wears a hat) and two girls, Mollie and Charlene, who don't bring much to the story. Due to his stupidity, ignorance and complete lack of any backbone Eddie makes a complete prat of himself on a school trip and is totally shown up by star pupil Courtney. Courtney is unfavourably portrayed as 'Little Miss Perfect' and the emphasis is that it is much better to not pay any attention in class and constantly josh your friends than be a socially adjusted human being. To pay her back for not being a pathetic looser, the team of misfits resort to theft, animal cruelty and fraud.
The final twist was far too predictable, from the moment Mud Monsters were mentioned, it was obvious they were going to be the final scare. Being Goosebumps, I suppose there has to be some horror element, but I think the ending would have been much better had Kevin and his friends scared Eddie and his friends, thereby teaching them a much needed lesson. There was no '...or were they?' ending this time.
I had read this before but had no recollection of any of it. Having read it again, I can see why.