For Aiden, Chloe, Ava and Josh, holidays at their grandparents’ cottage mean wild beaches, no curfew, Bella the dog, and most of all – adventure!

While sailing their Grandad’s boat along the coast with her cousins, Chloe sees a terrified face at a tower window on Thorn Island. Could the face belong to recently kidnapped young George, the only child of a rich local businessman? No one they tell believes there could be a child held prisoner in the tower. So, certain that the villains are hiding out nearby, the cousins must use all their skills and cunning to conduct a daring rescue.