Maximum Security Magic by Corinne O’Flynn

A witch, a vampire, and two ridiculously hot inmates find each other behind bars… sounds like the start of a bad joke, right?
But it’s all true…

After successfully breaking open a year-long case where my partner and I were undercover, it’s finally our chance to level up.
Something is not right at Shadowridge Academy, a reform school for supernatural felons. Inmates keep going missing, and nobody–not the prisoners, nor the guards… not even the warden–has been able to offer anything in the way of answers.
My partner, who also happens to be my sister, and I are members of the Myst Mages, an elite investigative force. We’re the ones they call if cases go cold in the magical world. When the team who went in before us misses their extraction, it’s up to us to go deep undercover. This means cutting off all ties with the outside world, including our friends, families, and even the force. If we break cover we’ll be disavowed.
The lives of countless inmates are at stake. With the help of some well-connected, and extremely handsome prisoners, we just might find out what’s happening and bring those responsible to justice… assuming we live long enough to see our extraction date.

Life at ShadowRidge Academy isn’t supposed to be a death sentence.