"In this mystery they were alone, for unlike the real world, with real detectives solving real disappearances, the people they were investigating were ghosts."

Arwin Argyle expects another boring day at school. Instead he is met with a series of disappearances, but only he and his classmate, Emma Li, of whom he has rarely spoken to before, remember those who have gone missing. Everyone else seems adamant that they’ve never existed at all.

Suddenly they are forced to discover who or what is behind the mystery at the school, before everyone they know…and each other…vanish into thin air.