It'd certainly be a plot twist.
How about the characters uncover a plot where they realize the school is pumped full of gases that make them believe the school is really nice and state of the art, and when they switch off the gases, the school reveals itself to be broken down and out of service for the last 3 years, all the students that were there before? They're gone. It's only the astrology club.
And then...
YOUR CHARACTER DIES. OO, mystery.