Birch plays two characters, alternating between them each time she falls asleep, each of whom believes that the other is a dream. The first of them, Karen Clarke, is a mortuary worker who awakes to find that she has injuries which she does not recall receiving, and the second is Susan Hamilton, an office worker who is preparing to undergo artificial insemination. As time passes Clarke’s world becomes increasingly nightmarish, with a corpse coming to life on her table and a serial killer stalking her, and the line between the two worlds becomes increasingly fragile.