There are many reasons why a book might be unavailable.
Sometimes a book goes temporarily out of print - and sometimes no audio version has ever been recorded. Audible wants to give you the most complete selection we can and we'll keep adding series and filling in gaps as quickly as possible.
The more instalments I read, the more I love Molly and her escapades!
On to book 6!
I love Rhys' books. She is a masterful story teller. I can't wait to read what's next!!