Winter and Arden Allister are two teenage sisters who've just moved from Memphis to San Francisco, and their interracial family is thrust into the bourgeoisie of San Francisco's elite once the girls begin the year at an exclusive private school. But when Winter starts having problems with a boy at school and Arden continues to suffer inexplicable and terrifying blackouts, each must follow a separate strand of fate out of their close-knit identity as sisters in order to unravel an arcane ancestral mystery. Once their futures are disentangled, Winter and Arden discover that destiny has drafted them both into the same magical battle of monsters and dominion—but placed them on opposite sides.