Kiera and Kyla Sparrow are twin sisters--humans, living very different lives. While Kiera is selfless, clever, and talented, Kyla is dark, duplicitous, and damaged--she belongs to a secret society of vampire-hunters, and she has sworn to destroy as many as she can. When Saxson's Blood Moon appears in a February sky, and the matching constellation, Cetus the Sea Monster, appears on Kiera's wrist, Kyla knows exactly what it means. The celestial gods have chosen her beautiful sister to be the eternal mate of an immortal vampire--she just doesn't know which one.