I have read this as well as the other Mr. Men books. Mr. Quiet lives in Loudland, where everybody and everything is noisy. This place would be suitable for Mr. Noisy, but not for Mr. Quiet. Mr. Quiet cannot do errands because the townspeople are too loud for him. But one day Mr. Quiet gets a letter from Mr. Happy to stay in Happyland where it is quieter. Mr. Quiet gets a job in a library(because everybody must be quiet in a library) and is so happy he laughs out loud. In terms of other Mr. Men being featured in the later books, this is one that mentions one(Mr. Noisy) but he is not seen. Hey, maybe Mr. Noisy moved into Mr. Quiet's old house in Loudland!