One night, Valerie decides to summon a demon, wishing it to obey her and grant all her wishes - but something goes wrong and it ends up commanding her instead. It needs a healthy, young body, and demands Valerie lure such a woman to the house for it, assuring her that he will not only release her, but fulfill all her dreams as well.
Valerie promptly moves, and shows her house to Sarah, newly single and looking for a place of her own. Sarah loves the isolation, and the peace and quiet it will provide, not to mention she can't resist the price - the only thing throwing her off is Valerie's demeanor. She's acting very strange, and appears absolutely desperate for Sarah to move in. Despite her slight hesitation, she falls in love with the house and agrees to take the place anyways.
Immediately upon moving in, Sarah begins to hear noises in the walls and under the floors. She is plagued by horrible nightmares. She finds a mutilated cat in the basement. Then there are the animals appearing in and around the house, with glowing gold eyes that seem to paralyze Sarah when she looks at them - the animals that project a voice into her head urging her to give into it and dismiss her self control.
Sarah realizes something is possessing these animals. There is an evil entity in the home, that can jump into whatever living creature it so chooses. She is able to ward off it's mental intrusions - but for how long? Instead of taking the easy way out, Sarah refuses to be driven from her home, and with the help of her best friends, and eventually Valerie, vows to fight this spirit and banish it once and for all.
-----------------
I have to say I don't really get why Jade (the spirit) didn't just possess Valerie if it wanted a body? Why didn't it just possess Sarah? Them being too strong would be the obvious answer, but that's clearly not the case, because it's able to get into theirs minds and make them do things whenever it wants. That's really the only thing I didn't get. I definitely did like the book though.