Lira has seventeen hearts in her bedroom. As a siren, she kills a human prince and takes his heart every year on her birthday. By doing so, she proves that she will be strong enough to take over her mother’s throne and become queen one day. However, after Lira disobeys her mother, she is punished by being transformed into a human — one of the creatures she hates the most. To win back her mother’s favor, Lira must claim the heart of Prince Elian, an infamous siren-killer and the heir to the most powerful kingdom in the land.