Dolphin twins, Mirus and Cetus, discover an anomaly deep in the ocean. The Elders believe their discovery is part of a secret to an ancient legend. The twins must decide if they will risk danger to help uncover the truth. Abby is in the space between childhood and adolescence and is trying to understand the world of adults. She spends most of her time alone on her sailboat, when she meets two strange children on her secret island. Although their story about how they got to her island and where they came from is strange, she decides to help them find their mysterious family member.