1911, New York. Seventeen-year-old Frances Hallowell works as a seamstress and mourns her brother, who died mysteriously a few months ago. Everything changes at once when her boss attacks her. Frances doesn’t understand how his corpse—with scissors sticking out of his neck—ends up at her feet… The police don’t even have time to accuse Frances of murder: two nurses come for her and take her to the sanatorium “Coldoston”—supposedly because she’s terribly ill. Soon, however, it turns out it’s not a sanatorium at all, but an academy for witches. The principal warns her new student about how dangerous strong magic is, but Frances knows little of the simple spells taught at the academy. She becomes enchanted by Finn, a mysterious young man who appears in her dreams and promises to teach her more intricate forms of witchcraft—those that will help her find her brother’s killer…