Black Diamond by Jennifer Loiske
Part One of McLean Twins Series
After her mom’s sudden death, twelve-year-old Shannon McLean has to move from the US to the English countryside to live with her mysterious father, Connor McLean, whom she hasn’t seen since she was a baby. Soon she discovers that he doesn’t want her around and her moving into his huge manor, Greyman Hill, is nothing more to him than a compulsory deal. But if he does not exactly give her a warm welcome, his servant Robert is most likely an incarnation of evil. He runs the house with an iron touch and makes everyone who works there his little puppets.
Weird things start to happen and the whole place scares the crap out of Shannon. Her dad can control her just by looking at her. The walls are full of secret passages and apparently she has the talent to awaken the ghosts in them. Every day is worse than the day before and she wants badly to run away but discovers it’s impossible. If she wants to stay alive she has to do exactly as her dad says or else she will not only jeopardize her own life but also the lives of the people around her.
While Shannon struggles to find the magic inside her, Connor is slowly turning into a demon. One carelessly spoken word from her could either save or destroy them both. In the end she has to decide whether to save herself and her loved ones, or lose her dad to the darkness and evil that threaten to eat his soul.