Beneath (2007)

In Edgemont, Montana, the teenager Christy Wescot is very connected to her beloved sister Vanessa Locke. On her fourteenth birthday, Christy asks Vanessa to drive her convertible car, but she has a car accident, hits a rock and is thrown off the seat; however Vanessa is trapped in the car that explodes and she survives disfigured and totally burnt. Christy is sent to Pine Bluff Psychiatric Care Center for treatment while her sister is treated by her husband Dr. John Locke at home with the assistance of the nurse Claire Wells. When Vanessa has a heart attack and dies, Christy has a breakdown in the funeral service telling that her sister is alive in the coffin. Then she moves to California for the pre-med, but is haunted by nightmares and weird visions. When the caretaker of the family Joseph dies six years later, Christy returns to Edgemont for the funeral and has a cold reception by John and his mother. However, her niece Amy that is afraid of "dark things" behind the walls of the house asks her to stay in the town for a couple of days and Christy's friend Debbie welcomes and lodger her in her house. Christy has mysterious blackouts with strange visions and decides to investigate the death of her sister that she believes had been buried alive, disclosing a dark secret, while the locals believe she has borderline personality disorder.