A field trip to a mysterious island quickly turns into an adventure when Emily and Aaron discover a ghostly ship that no one else can see. Searching for answers only leads to more questions -- until Emily and her friends uncover the story of a ship caught between land and sea, day and night . . . life and death. Only Emily, with her ability to transform from mermaid to human, can enter Atlantis to try to bring the ship's passengers back before the portal is closed forever. Will she be able to resist the allure of Atlantis and return home before it's too late?