When Francie, Melina, and Andreas find a bottle washed up on the shore of ancient Elounda after a strong storm, an adventure begins for the children that they never expected to experience. What does the key inside the bottle open, and who wrote the note that accompanied it? How much will the wise antique dealer of Agios Nikolaos help them? What role will the elderly painter who exhibits her works in Spinalonga play in all this? Or could all these events be the reason for them to discover something much bigger?