Devastated by the loss of their unborn baby, Kate (Vera Farmiga) and John (Peter Sarsgaard) decide to adopt a child. At the orphanage, both feel drawn to a little girl (Isabelle Fuhrman) named Esther, and soon the couple take their new daughter home. But when a dangerous series of events unfolds, Kate begins to suspect that there is something evil lurking behind the child's angelic exterior.