On Thalassa, graduate student Mira Hale thinks she’s found the perfect subject for her thesis: a lone Siren she mistakes for a shy merman who needs help with courtship. But her mating dance awakens something far more dangerous—Auren, the deep-sea hunter, claims her as his destined mate. Whisked away to his underwater cave, Mira is forced to face the mystery of her own forgotten past, where a childhood rescuer has been waiting for her all along. As old fear and new trust collide, their impossible connection becomes a love that defies the galaxy.