Three children from Athens, a boy from Volos, a girl from Maroneia, her little brother, and two boys who speak Turkish, become a group at the beach of Maroneia where they meet.

They decide to unravel the mystery of the oil on the lawn and its connection to the stolen relic, as well as the strange presence of the Russian princess.

They will never know who sent the misspelled message, but they are certain that the cellar hides secrets.

With their observant nature and cleverness, they help capture the antiquities thieves and return the precious relic to the Folklore Museum where it belongs.

The cobbled streets of Komotini, the park, and its historic buildings, as well as the roasted chickpeas and the soutzouk loukoum serve as the canvas upon which the adventure of the children unfolds, making promises of everlasting friendship.