The Doors - Alice J Black

When she is moved halfway down the country during the summer holidays, Amanda finds she's stuck in a place that she not only hates but where it never seems to stop raining. Godfrey Hall, their new home, is a dark, cold place that she can't seem to adjust to. The worst room is the dining room where a set of mosaic doors seems to draw her in despite the fact that she despises it. The first day her parents are both out, Amanda finds out the true secret of the mosaic doors and nothing will stop her opening the shrine made for a man hundreds of years before her.