After New Orleans hospice worker Caroline (Kate Hudson) answers a help wanted ad, she finds herself working as the live-in caretaker of Ben Devereaux (John Hurt), a stroke victim who has lost his ability to speak. Ben's wife, Violet (Gena Rowlands), presents Caroline with a skeleton key to open any door in the house--with the exception of one, which she claims she has never been able to open. But curiosity gets the best of her, and Caroline opens the door to find a wealth of materials representing the old house's history of hoodoo, an ancient form of folk magic. She soon discovers that the house harbors a dark secret--one that Violet knows more about than she first admits.