Descent (Son of a Mermaid)

Shea MacNamara's life just got complicated. When a freak tornado devastates his Oklahoma farm, fifteen-year-old Shea moves to Cape Cod to live with a grandmother he's never met. Struggling to make sense of his new surroundings, he meets a girl along the shore who changes his life. Forever. Kae belongs to an undersea world hidden from humans, where bloody war rages between opposing clans. A fragile peace accord hinges on marriage between the royal families, but treachery and magick lurk in every shadow. With Kae's help, Shea discovers his true heritage and finds that his destiny lies somewhere far below the ocean's surface.