There are 2 books in The Adventures of the Princess and Mr. Whiffle series.
The Adventures of the Princess and Mr. Whiffle series does not have a new book coming out soon. The latest book, The Dark of Deep Below (Book 2), was published in December 2013.
The first book in The Adventures of the Princess and Mr. Whiffle series, The Thing Beneath the Bed, was published in December 2012.
The Adventures of the Princess and Mr. Whiffle series primarily falls into the Horror genre.