Jonny is turning 18, and things are happening that lead to her dad sending her to live with her Aunt Hildie—someone who, alongside the people at Jonny's new school, are notably strange.
"Perpetrator" has decent social commentary as it pokes fun at what society has pushed to seem normal, even though the norm is what is truly horrifying.
You can enjoy "Perpetrator" if you can accept that it operates like an action movie, where blood and setting up situations to see it matters more than characters or story.