Every weekend, 16-year-old Ivy Medina sinks beneath the waves and explores the ocean of the beach she lives on. But on this already peculiar day, she conjures a most vivid dream where she discovers an underwater tunnel that leads her to the captivating world of Harukai.

Only, Harukai is anything but a dream, and upon returning home, everything she’s ever known is quite literally torn from her hands as her mother is taken captive. Now trapped in Harukai with the loss of her mother and her own identity pulling her under, she ends up living inside a tree, inherits a pile of old books, and finds a sword made of glass.

With a mysteriously friendly faun and a flirtatious yet slightly irritating merfolk by her side, Ivy scours old tomes and learns how to fight, all in the name of finding a way home and rescuing her mother. But her search has her questioning everything she knows, leading her to uncover her hidden identity and the truth about her past, her present, and her future.