Devilish:

At St. Teresa’s Preparatory School for Girls in Providence, Rhode Island, rebellious senior class genius Jane Jarvis is worried about her best friend Allison Concord.

Ally is lovable, but a little clueless, and badly in need of Jane’s help. She needs to get a freshman “sister” at the school’s annual Big-Little celebration. When Ally blows it (rather literally), Jane knows that they are in for a rough few weeks.
She has no idea just how rough they will be.
Strange things start happening in Providence. Hail storms rip into the city. A strangely polite gourmet in a silver roadster turns up every time Jane turns around.

A freshman guy from neighboring St. Sebastian’s starts to stalk her. A lanky, cupcake-loving sophomore transfer steps into their lives to save the day . . .
Then Ally begins to change. She looses the awkwardness that Jane has always known and loved and becomes the model of cool.

Things don’t go as well for Jane, and she soon winds up facing the threat of expulsion and ruin.
But these are only the beginnings of much bigger problems. Jane’s life is about to get much worse. Ally claims that she sold her soul, and Jane throws herself on the line to get it back. But this battle is big. A crowd of strangers is about to descend on Providence, and they’re not there to go on a campus tour of Brown.
It’s Jane versus the demons, and nothing is what it seems. There will be perfume bottles, dogs, explosions, dancing, death, badly misused textbooks, ex-boyfriends, very long falls, unusual weaponry, and lots of sugary snacks before it’s all over.

Hey, you do what you have to do. Everyone knows high school is hell.