On Halloween 1993, deep in the Department of Mysteries in Magical Britain, an experiment goes wrong and because of this, monsters gain a foothold past the barriers that separate the human world from the other realm and they begin to wreck havoc around subtly.

In Hogwarts, two unassuming girls, Sally Anne Perks and Luna Lovegood start to realize something is wrong, and because of how much it seems to affect them, they decide to try to fix what is wrong in Hogwarts, while also a serial murderer runs rampant around the school.

It's just another year for the students of Hogwarts, don't you think?