The Five Find-Outers

1. 

   Book 3

   The Mystery of the Secret Room

   Enid Blyton

2. 

   Book 4

   The Mystery of the Spiteful Letters

   Enid Blyton

3. 

   Book 5

   The Mystery of the Missing Necklace

   Enid Blyton

4. 

   Book 6

   The Mystery of the Hidden House

   Enid Blyton

5. 

   Book 7

   The Mystery of the Pantomime Cat

   Enid Blyton

6. 

   Book 9

   The Mystery of the Vanished Prince

   Enid Blyton

7. 

   Book 10

   The Mystery of the Strange Bundle

   Enid Blyton

8. 

   The Mystery of the Burnt Cottage

   Enid Blyton

9. 

   The Mystery of the Disappearing Cat

   Enid Blyton

10. 

    The Mystery of the Invisible Thief

    Enid Blyton

11. 

    The Mystery of the Strange Messages

    Enid Blyton

12. 

    The Mystery of Holly Lane

    Enid Blyton

13. 

    The Mystery of the Missing Man

    Enid Blyton

14. 

    Still more Mystery Stories (The Mystery of Banshee Towers / The Mystery of the Burnt Cottage / The Mystery oft the Disappearing Cat)

    Enid Blyton

Book data and covers from Open Library (openlibrary.org).