Miylani, a young mermaid whose imagination is her only friend, dislikes her boring life and the isolated and gloomy sea in which she lives. She looks different than the other mermians swimming around her in Treemont, a large community hidden beneath the floor of the Platoonic Sea. All the other mermen and mermaids call Miylani mysterious, and she has no idea why. Eager for excitement, one day, she disobeys her father's orders and follows her twin brothers through the seaweeds into forbidden waters. After she learns her brothers are there to retrieve a lost sword, they swim behind a stone that quickly closes before Miylani can catch up. When she decides to wait for them to re-emerge and becomes entangled in the seaweeds, Miylani begins to experience strange happenings that eventually lead her to discover her magical abilities and surprising secrets with the power to alter her life and the entire sea world. In this exciting tale, a mysterious young mermaid enters forbidden waters where she unearths her magical powers and secrets of the sea.