Breakaway (The Blighted Trilogy Book 1)

Details: 

Thea Galleon is looking forward to her mermaid Tail Ceremony on her 19th birthday until she discovers she was adopted, and worst of all is suspected to be human. Accused of treason and she sets out with her best friends to escape the island of Bailerunda in a race to discover the truth, and who, or what, she will ultimately become.