Alexandros, Lambis, Christina, and Jorge are students in the 2nd year of middle school, and they take on a project in their History class about the Walls and the Moat of the Medieval City in Rhodes. They read books, gather information from the internet, and film the sights of the area.

Through the project, they get to know each other better and appreciate the value of friendship, cooperation, solidarity, and love. During a visit to the Moat, they decide to explore the underground tunnels. There, completely by chance, they find a map filled with riddles and sketches.

What is this map, and where will it lead them? The last sketch shows a “Sun.” They summon their knowledge, and together they begin to decipher the riddles one by one, progressing deeper into the damp and dark tunnels. The air is diminishing, the water is running out, and some get injured.

However, they want to reach the end. They believe they will find hidden treasures… What will they ultimately discover, and how will they manage to emerge alive from the tunnels? A children's novel about Rhodes, based on its history. A literary-educational manual with rich photographic material of historical monuments. A modern fairy tale for the island of the Sun, aimed at children from 9 to …99 years old.