The historical plot occurs in the aftermath of the Salem Witch Trials in Massachusetts and features the confession of Anne Putnam, one of the girls "bewitched" during this bizarre period of American history.
The modern plot is reminiscent of an incident that took place in Le Roy, NY in 2012, but as a means of writing her own story, the author has chosen to re-set her fictionalized version in Danvers, MA. The story follows a group of girls who begin to experience some strange symptoms including seizures, fainting, twitching, stuttering, etc. While none of these symptoms would be unusual in one girl, the fact that by the end of the book, over 50 girls are affected causes panic in the community. The main character Colleen struggles to understand what is happening around her while also trying to maintain her normal life as a high school senior.
Probably most entertaining to me was the cast of adult characters who react in all too realistic ways to this assault on their children, but I think young adults will prefer to watch Colleen try to unravel what gets coined as the Mystery Illness.