Four-year-old half-blood Maisie Blackthorn, after her mother Rowan Vale’s death, hides in a coffin wagon and reaches Blackthorn Castle to find her father, Duke Alaric Blackthorn. Her blood awakens the broken Blackthorn crest and the blood wards, forcing the cold vampire duke to acknowledge her. Through her ability to hear heartbeats and sing Rowan’s moon song, Maisie helps expose the poisoned red draught, Finn’s suffering, and Regent Cedric’s conspiracy with the Holy Sun Church. The Bloodheart’s memories prove that Rowan never betrayed Alaric: Cedric poisoned her with silverroot, forged evidence of treason, and made Alaric believe she had stolen the Bloodheart. On the Red Moon night, the Church and the twelve lords attack Blackthorn Castle; tainted blood drives soldiers into frenzy. Maisie uses the Bloodheart and her mother’s song to calm the frenzy and save Alaric. After the truth is revealed, Cedric is imprisoned, the Church retreats, Alaric names Maisie his lawful heir, abolishes the restrictions against half-blood children, and rebuilds the Moon Tower as the Rowan Vale Moon Tower Clinic. Father and daughter finally go home at dawn.
