The Blue Tail — Kim Antieau

SERENA BLUE LIVES for one thing: to spend time with her boyfriend. She can't stand the stories of the Old Mermaids her mother constantly tells, and she suspects her own family's sanity when she learns her grandmother believes she once lived as a mermaid. Lost and unsure of where her life will lead, Serena casts about for something to believe in. When the truth of her grandmother's past surfaces, Serena must struggle for her own survival and uncover the difference between reality and delusion.