Marissa Anselmo and the City Beneath the Sea — Russell James

At sixteen, Marissa Anselmo discovers she has a choice. She can live a life above the water or beneath it. Thousands of years ago, sorcerers separated two warring Mediterranean peoples, teleporting satyrs into northern Europe, and submerging the human's island of Atlantis beneath the sea. Satyrs' powerful lower limbs were turned into mere human legs, and Atlantisian legs were transformed into tails. Marissa discovers that her mystery father was from Atlantis. Her half human/half mermaid status attracts satyr agents who want her physiological secrets and Atlantis's hidden location. Guardians from Atlantis foil her kidnapping and whisk her to visit their city beneath the sea. Eric, the boyfriend she leaves behind, has his own revelation as his father explains their satyr heritage. Though neither knows it, a future together m,ay be impossible. But all in Atlantis is not as it appears, and the leader's secret plot would turn Marissa into an agent of death for thousands on the surface, including Eric.