Ada and Harriet don't know what to expect when they meet their new guardian, Mr. Wolfson. Here is a strangely magnetic, darkly amusing man confined to a wheelchair and flanked by a pair of fierce, dangerous dogs—an enigmatic benefactor, at once welcoming and intimidating. Even more unsettling to the girls are Wolfson's two sons, Julian and Francis. One of them is warm and good-natured, the other is pure malevolence. But young Harriet is about to discover a frightening truth: that evil runs rampant throughout their mysterious new home, Abbey Manor, and the surrounding moors—especially when the moon comes out . . .