To Kill a Kingdom book by Alexandra Christo

I have a heart for every year I've been alive.

There are seventeen hidden in the sand of my bedroom. Every so often, I claw through the shingle just to check they're still there. Buried deep and bloody.

Princess Lira is siren royalty and revered across the sea until she is cursed into humanity by the ruthless Sea Queen. Now Lira must deliver the heart of the infamous siren killer or remain a human forever.

Prince Elian is heir to the most powerful kingdom in the world and captain to a deadly crew of siren hunters. When he rescues a drowning woman from the ocean, she promises to help him destroy sirenkind for good. But he has no way of knowing whether he can trust her …