The Enid Blyton Secret Series - Season 2
1 - The Secret Of Spiggy Holes 1
The children, reunited with their parents again (and Jack now adopted as part of the family), go on holiday at the rugged Cornish coast with a family friend, Miss Dimity, and get drawn into a kidnapping case as they discover a boy being held prisoner in a castle tower nearby.
2 - The Secret Of Spiggy Holes 2
3 - The Secret Of Spiggy Holes 3