The fourth book in the adventure series by the most beloved children's author in the world.

Jack, Lucy-Ann, Philip, and Dinah, along with their parrot, Kiki, go on vacation to the northern seas of Scotland. There, their friend Bill, the secret policeman, follows them.

However, as the four friends enjoy the wild nature, they realize they are not alone. Suddenly, the carefree vacation turns into a chase.

Who is the mysterious Horace Tipperlong who introduces himself as a nature lover? Why are planes flying over the deserted islands?

Are you ready for... an adventure?