The Enid Blyton Adventure Series

Book 4: The Sea of Adventure (Part 1) (1x10)

Air date: Aug 11, 1996

The family have arrived in New Zealand. They are met by Bill's friend and colleague - Dennis who needs Bill's help to solve the mystery of a missing agent who was investigating a villain, Perez. Bill's not interested but finds himself involved anyway. Perez has his sidekick, install a tracking device on it and makes plans to insure Bill and the children pose no threat to his nefarious scheme.