Darkwater

It is a life-changing deal—and it will end your life as you know it.
 
Sarah Trevelyan would give anything to regain the power and wealth her family has lost, so she makes a bargain with Azrael, Lord of Darkwater Hall. He will give her everything she needs to restore the Trevelyan name, and one hundred years to do it—in exchange for her soul. Fast-forward a hundred years to Tom, who dreams of attending Darkwater Hall School. A professor named Azrael offers him a bargain. Will Sarah be able to stop Tom from making the same mistake? Catherine Fisher's version of Faust is utterly spellbinding!