Escape from Peruácru Island

There were once a brother and sister who would shrink themselves with red potions and explore the world from the back of a giant paper airplane. They discovered an uninhabited island amid the sparkling Pacific ocean and named it Peruácru. They alighted upon a green knoll and drank their blue growing potions, only to damage their plane and lose their stock of potions. The clever pair set out to explore the island and hopefully find a way home with their four hands and two cunning heads.