In the wake of the Delos family’s arrival on Nantucket, Helen Hamilton’s life is upended not just by ancient feuds, but by the arrival of the sister she never knew she had: Selene. Raised in secret by their mother Daphne, Selene is Helen’s lethal reflection; a golden-haired warrior with a rebellious spirit and a striking hourglass figure. To prevent a catastrophic prophecy, Daphne weaves a devastating lie, claiming Helen is the daughter of Ajax. This makes Helen’s love for Lucas a blood-sin.