It's senior year at St. Joan's Academy, and school is a pressure cooker. College applications, the battle for valedictorian, deciphering boys' texts: Through it all, Colleen Rowley and her friends are expected to keep it together. Until they can't. First it's the school's queen bee, Clara Rutherford, who suddenly falls into uncontrollable tics in the middle of class. Her mystery illness quickly spreads to her closest clique of friends, then more students and symptoms follow: seizures, hair loss, violent coughing fits. St. Joan's buzzes with rumor; rumor blossoms into full-blown panic. Soon the media descends on Danvers, Massachusetts, as everyone scrambles to find something, or someone, to blame. Pollution? Stress? Or are the girls faking? Only Colleen - who's been reading The Crucible for extra credit - comes to realize what nobody else has. Inspired by true events - from seventeenth-century colonial life to the halls of a modern-day high school, this is the mystery that raises the question, what's really happening to the girls at St. Joan's?