House of Many Ways by Diana Wynn Jones is the sequel to Howl's Moving Castle. It is the story of Charmaine Baker who is taking care of her Uncle William's house while he is in the care of the elves.
Charmaine has many adventures in the house. It has doors which lead to all sorts of odd places like a path to the castle, the kobold's workroom, the cistern, the wizard's library, the ballroom, and various other places.
The story has many twists and turns. Charmaine becomes assistant librarian to the king and princess, helps solve a mystery with the royal mint, and must contend with the evil lubbock and his lubbockins.
The setting is a kind of magical victorian kingdom. It mainly occurs in the magical House of Many Ways, the royal castle, and Charmaine's fathers magical bakery.
The characters are entertaining, Waif the dog, Rupert the Kobold, Peter, and the royals. It isn't until halfway through the story that Calcifer, Howl, and Sophie show up in the book.
The writing is charming and easy to follow. It is written in a style that is appealing to both adults and children. The content is appropriate for all age levels. Even though, it is 401 pages long, it is still fairly quick to read. There is very little excessive verbiage.