Child of Darkness by Virginia Andrews
She grew up in the shadows of lies. Now the past will come to light ...As a child, she was Baby Celeste, the one thing that kept her mother in touch with reality. But now her mother is in an institution, and 16-year-old Celeste Atwell is alone in the world. Adopted by a wealthy couple, Celeste has everything a girl could desire: designer clothes, luxury cars, even a handsome boyfriend. But her indulgence may come at a steep price - because the secrets hidden within her new family are too dangerous to keep under wraps ...