When he couldn't save a little girl who was being abused by her father, policeman Jack Nightingale left the force and became a private investigator. But he's struggling. That is, until he inherits a mansion in Surrey from a man who turns out to be his biological father. A father, who, it appears, killed himself in the middle of a magic circle when he was unable to reverse a deal he did with a demon. A deal that sold his son's soul.