For many, Shadow School is an ordinary school, but not for Cordelia Liu and her friends, because they know that their school is infested with ghosts! When the kids return from vacation, they discover that there are even more ghosts in the school. The teachers behave strangely - they look at the students with glassy eyes and go to secret meetings every day.

Cordelia is sure that something truly terrible is happening at Shadow's school, and tells her friends about her suspicions. But they don’t seem to care: Benji has started dating a girl, and Agnes spends her days reading her textbooks. It seems that no one except Cordelia cares that Shadow's school is in very great danger! And then she decides to act alone...