For three years running, on the exact same day in May, six students vanished from Erica Trestle's high school. The adults deny anything unusual is happening, claiming the teenagers went on exchange programs or moved to other cities. But to Erica, their explanations seem absurd. Why were families moving without warning in the middle of the night? Why wouldn't the students tell their friends they were going on an exchange program, and why didn't they return? When two of the missing teenagers reappear-one catatonic and one dead-most of the students become convinced they are in danger. As the day rolls around again, Erica and her friends scramble for ways to protect themselves against the threat no adult, not even the police, seems to take seriously. In the face of their indifference, Erica is certain the disappearances are a part of a vast conspiracy, more dangerous than anyone imagines. What she doesn't realize is that this year-it's her turn.