Adelaide Foss, Maggie Borland, and Beatrice Alfred are known by their classmates at Widowsbury's Madame Gertrude's School for Girls as "scary children." Unfairly targeted because of their peculiarities—Adelaide has an uncanny resemblance to a werewolf, Maggie is abnormally strong, and Beatrice claims to be able to see ghosts—the girls spend a good deal of time isolated in the school's inhospitable library facing detention. But when a number of people mysteriously begin to disappear in Widowsbury, the girls work together, along with Steffen Weller, son of the cook at Rudyard School for Boys, to find out who is behind the abductions. Will they be able to save Widowsbury from a sinister 12-year-old curse?