After shooting her little brother dead, Annie Radford is sent to a psychiatric hospital for assessment. Hearing voices in her head, Annie is forced to undergo experimental new treatments devised by a mysterious old man who lives in the hospital's attic. It soon becomes clear that the hospital's staff, led by the vicious Nurse Winter, are involved in some dark and horrific plans. As Annie struggles to survive the hospital, she learns more about Nurse Winter's own story. Once a promising young medical student, Nurse Winter also heard voices in her head. What kind of signals are being transmitted from the basement of the hospital? Who is the old man in the attic? Why are living human brains kept in jars? And what is the dark secret that lurks at the heart of the hospital?