There's a monster in the ocean, lurking deep below the surface. And ever since her becoming a mer, Liesl has sought only to please it. But everything changes when she's caught committing a crime that confirms her death. Liesl is to die in a week, offered up to the monster Cyanea as a sacrifice, along with a newly turned mer, Halley. The only way of survival is to escape the beautiful ruins of Merfynia Liesl has for years called her home, and with time running out, it seems to be the only option they have. Now all they need is a kiss from a mortal to regain their legs -- but, in the ocean wilds, nothing is ever that easy, and survival will take more than a flick of their tails.