Monday Charles is missing, and only Claudia seems to notice. Claudia and Monday have always been inseparable. So when Monday doesn’t turn up for the first day of school, Claudia’s worried. When she doesn’t show for the second day, or second week, Claudia knows that something is wrong. But Monday’s mother refuses to give Claudia a straight answer, and Monday’s sister April is even less help. As Claudia digs deeper into her friend’s disappearance, she discovers that no one seems to remember the last time they saw Monday. How can a teenage girl just vanish without anyone noticing that she’s gone?