When her friend Monday Charles goes missing and Monday's mother refuses to give her a straight answer, Claudia digs into her disappearance. Monday Charles is missing, and Claudia seems to be the one person who notices. They've always been inseparable, and when Monday doesn't show up for school for two weeks, Claudia knows that something is wrong. Monday's mother refuses to give Claudia a straight answer, and her sister April is even less help. How can a teenage girl just vanish without anyone noticing that she's gone?