When Alexis's little sister Kasey becomes obsessed with an antique doll, Alexis thinks nothing of it. Kasey is a weird kid. Period. Alexis is considered weird, too, by the kids in her high school, by her parents, even by her own Goth friends. Things get weirder, though, when the old house they live in starts changing. Doors open and close by themselves; water boils on the unlit stove; and an unplugged air conditioner turns the house cold enough to see their breath in. Kasey is changing, too. Her blue eyes go green and she speaks in old-fashioned language, then forgets chunks of time.
Most disturbing of all is the dangerous new chip on Kasey's shoulder. The formerly gentle, doll-loving child is gone, and the new Kasey is angry. Alexis is the only one who can stop her sister — but what if that green-eyed girl isn't even Kasey anymore?