From the introduction:
It is assumed that the Player Characters are members of the Eastside Project, a secret organization dedicated to the capture and elimination of Outsider threats to our dimension. If your group is not members of ESP, you will need to decide how to introduce the party to the plot.
A Deva sings for a gothic metal band called Pantomime. She is using her magical abilities to seduce the crowd, and hypnotizing them into committing crimes.
Several fans have gone missing after having gone to Pantomime’s shows. Some of the fans have been involved in riots and other crimes of passion following their shows. Local police have dismissed the incidents as unrelated, but the Eastside Project thinks otherwise.
The truly evil people in the audience are compelled to act out their dark desires and then turn themselves in. Persephone, the Deva, believes that she is exposing the evil people in the crowds and that justifies her actions.