Mysterious, frightening things begin to happen at Marina’s house. Once again at the bottom of the Mediterranean Sea, she faces new challenges and learns that the throne beneath her is swaying. Who and why has the right to take the throne from her? During her second visit to the kingdom, she will have to survive the rainy season, learn the history of the founding of Marinia, attend the show of the most famous underwater fashion designer, find herself in the center of a religious and political scandal, encounter horrifying phenomena and celebrate the most a controversial holiday in the underwater world - Neptune Day. A girl from Odessa will not only solve new mysteries hidden in the depths of the sea, but will also learn about the secrets that her hometown keeps.