Return To Grayworld

Is the sequel of the 59th book The Haunted School of the original series although it has the same amount of chapters(30) as the first book there is a lot more background info that wasn't present in the first book including the mysterious Mr. Chameleon's physical appearance and the real reason he keeps trapping kids in the colorless classroom,Thalia's first few days once she escaped Grayworld as well as a bit of information on her and her friends' past lives in 1947 Bell Valley,Grayworld's origins,Greta's actual role in the story and go on and so forth.