Aria is a professional mermaid at an aquarium. She wears a fake tail and performs for visitors. All her life, she has been in love with the mythical creatures, but her whole world is turned upside down when they turn out to be more than myths and she gets caught in the middle of feuding cities from deep under the sea.

In this sequel to the award-winning novel, "Tails", Aria discovers what it's like to have a real mermaid tail, but the deep-sea cities are not the fairy-tale wonders she dreamed of and she quickly finds herself falling deeper into their problems while still trying to manage her life on land. Torn between worlds, Aria must figure out what it is she truly desires.

In this exciting conclusion to the Transformations trilogy, Aria and Alizarin meet other red-tails who seem welcoming, but have a plan that could change everything for the merfolk. Aria must decide who and what she truly wants. All fates will be decided as the comet draws nearer and everyone must choose who they wish to be.