At the end of the 9th grade, Katie Terosie learns that her family is moving to St. Thomas in the US Virgin Islands. She is devastated about the move and leaving her friends in Minnesota. That is, until she meets her new neighbors, Seth and his sister, Lauren. While snorkeling, Katie finds a map in a bottle at the bottom of the Caribbean Sea. Katie, her younger sister Anna, Seth, and Lauren decide to follow the map. They discover that they can magically breathe underwater and, in a short time, find themselves in a tricky position. They are in a world of mermaids, mermen, and all kinds of...