The ominous official trailer for Shut In opens with a woman (Naomi Watts) washing a teenaged boy (Charlie Heaton) in a bathtub. She tries to drown him, then suddenly wakes from her dream. It turns out she's taking care of the boy, who seems to be in a coma. She tells a man there has been no change since her husband died - in a car accident while the boy was in the seat beside him. Working as a child psychologist, she brings a grieving young boy named Tom (Jacob Tremblay) into her home. But during a snow storm, Tom disappears. Mysterious things begin happening, and as the woman's lying in bed, a hand covers her mouth. Although others say she's just having nightmares, she claims they are real.