Dr. Miranda Grey, a psychiatrist at Woodward Penitentiary in rural western Connecticut, crashes her car one night on a country road to avoid hitting a young woman. When she awakens, she finds herself an inmate of the women’s ward in which she works, receiving treatment from her colleague, Dr. Pete Graham. Pete reveals that her husband, Douglas, has been the victim of a brutal axe murder, and she is the sole suspect. As Miranda attempts to adjust to life as an inmate, she is haunted by visions of the young woman she saw the night of the car accident, and is attacked by her apparition; the woman carves the phrase “Not Alone” into Miranda’s arm, though hospital staff presume she is self-harming.