Psychiatrist Rand Morrissey is faced with a quandary when he is consulted on the baffling case of five-year-old Sienna, who has been suffering from unexplained fainting spells. Then he discovers that Sienna has a half-sister, Chelsa, who has been in a coma since a car accident six years earlier, something the girls' manipulative mother Melanie Cantrell has kept secret. When she is questioned under hypnosis, Sienna reveals things only Chelsa could have known. Rand begins to suspect that Melanie is machinating Sienna's problems. Or is she? Now Rand must overcome his own childhood demons and find a way to save the lives of two half-sisters, inextricably tethered between life and death.