Complex sentence: The book is somewhat different from others in the series, in that the story takes place on a highland moor, rather than at the Kirrin Island or Kirrin Cottage as with most of the other books.
Split into simpler sentences: The book is somewhat different from others in the series, in that the story takes place in a different setting. The adventure takes place in a highland moor, rather than at the Kirrin Island or Kirrin Cottage as with most of the other books.