Sixteen-year old mermaid Maya is harboring secrets: her sister’s forbidden human boyfriend (and her own crush on his charming cousin); what really happened the night her friend Gemma disappeared; and worst of all, her overwhelming urge to sing. Only sirens sing, and sirens are murderous enchantresses. Mermaids caught singing are banished. But when a human hunter attacks her friend on a training excursion, Maya’s song bursts out, driving back the attacker and freeing her friend, with the help of three sirens.

Another friend doesn’t make it back from the excursion and Maya is sure she’s been captured by hunters—just like Gemma. But the Mermaid Council suspects sirens. Dismayed by her pod’s failure to recover the missing girls, Maya seeks help from her sister’s boyfriend and his cousin, and from the sirens—including the captivating but cold Kai, whose song Maya can’t stop humming. Risking banishment and capture, Maya races to master her song, track down the hunters, and rescue the missing mers, before any more disappear. As the attacks escalate, Maya must choose between retreating to the safety of her pod or embracing the sirens’ dangerous freedom. And that means deciding whether her song is a curse to be freed from, or a gift worth fighting for.