Trama

Caroline (Kate Hudson) is a young hospice worker who is disillusioned by the reality of this type of work. She is despondent about the death of her own father, who died alone because she was unaware of his situation and was living life on the road with a traveling rock band. Caroline feels guilty about this and has devoted herself to becoming a person who makes a difference.

Caroline finds herself confronted by the same type of avoidance that she gave her own father when a patient dies and nobody from his family is even interested in picking up his belongings. The last straw comes when Caroline finds boxes of items belonging to other recently deceased patients, all being stored in a dumpster, thrown out as garbage. Caroline quits her job at the hospice and follows up on a lead for a position as a personal care assistant.

A lawyer named Luke (Peter Saarsgard) fields the phone call from Caroline, and he sets up an interview with the family. Caroline visits the secluded New Orleans home, which is an old mansion near a bayou swamp, and meets her potential employers. She will be caring for Ben Devereaux (John Hurt), who seems to have suffered some kind of stroke. His wife, Violet Devereaux (Gena Rowlands), seems to immediately dislike and distrust Caroline, but Luke smooths it over and encourages Caroline to take the position. Perhaps because she finds Ben's condition compelling, Caroline accepts and moves into the mansion.

On her way there to move in, Caroline stops by a rural gas station and notices odd details around the rundown facility, including a line of red dust that has been placed across the threshold of the building. The strange proprietors have hung animal bones and other talismanic items around the place.

Caroline settles into the mansion and notices that all the mirrors in the house have been removed, seemingly recently. Violet warns Caroline that she's decided to take them down and Caroline is not to replace them. Violet gives Caroline a "skeleton key", which is intended to open every door in the huge house, but she finds a strange, small door in the attic that it does not unlock. Caroline is intrigued, seeing as Ben supposedly suffered his stroke in the attic. When she questions Violet about the small room, Violet says she's never been in the room because she could not unlock it.

Ben's condition alarms Caroline from the start. He does not appear to be a stroke victim, but actually seems paralyzed by some other means. Violet has Caroline administer "remedies" to him periodically, but when they are alone, Ben seems to be trying to tell Caroline that he is in danger. One night Caroline finds that Ben has somehow climbed out onto the roof outside his bedroom window, and he falls a short distance to the ground. Retrieving Ben's wheelchair, Caroline finds that Ben has written "Help Me" on his bedsheets, using soil from a potted plant. After hiding the bedsheet, she returns with the wheelchair, but Violet refuses to call a doctor.

Caroline eventually gets into the locked attic room and finds a large collection of bizarre items that are obviously intended to be used for some kind of magic. She also finds all of the house's mirrors, she she hangs one in Ben's room, much to Violet's horror. Caroline finds out a little about magic from her friend and former roommate, Jill (Joy Bryant). Jill seems to think that the magic in question is Hoodoo, a type of folk magic which, unlike Voodoo, is not related to any kind of religion. Jill mentions that Hoodoo only holds power over those who believe in it; if you do not believe, its spells can't harm you.

After visiting the secret room again, Caroline unearths a vinyl record that is labeled "The Conjure of Sacrifice". She takes it to her own apartment so that she can listen to it in private, and it contains Papa Justify's voice reciting an incantation.

Later, after a confrontation about the strange goings on, Violet explains the mansion's sordid past to Caroline. Years ago, the house was occupied by wealthy white owners. A pair of black servants, Papa Justify and Mama Cecile, were brutally attacked and lynched during a party that was attended by many wealthy, powerful guests. They were apparently well versed in the ways of Hoodoo, and Justify had even discovered a unique spell that was called the Conjure of Sacrifice. Justify and Cecile were discovered in the attic conducting a magic ritual with the two small children of the house, and the party guests reacted by dragging them outside, hanging them from a tree, and burning their bodies. Violet tells Caroline that she has removed all the mirrors from the walls because you can see the spirits of Justify and Cecile in the mirrors.

Seemingly anxious to put this to the test, Caroline uses her small compact mirror and holds it up to Ben's face while she is bathing him. After looking into the glass, Ben reacts in horror, and Caroline feels that Ben believes in Violet's superstitions. She gets the idea to visit a woman that Jill has told her about, a woman who sells magic items from the back of a public laundromat. Caroline describes Ben's situation to her and the woman gives her a spell intended to reverse whatever hex has already been placed on him. When Caroline enacts the spell, Ben begins to speak to her, begging her to help him, but Violet interrupts.

Caroline confides in her suspicions to Luke, who seems to accept her theories about magic but also does not take them very seriously. When Caroline attempts to show him the bedsheets that Ben wrote "Help Me" on, she finds the message is no longer there. She takes Luke to the gas station where she saw the magic items, and she now recognizes the dust sprinkled across the doorway; this is red brick dust, which she has learned is intended to keep one's enemies at bay. In one of the shacks behind the station, Caroline finds an old woman listening to vinyl records just like the ones in the Devereaux's attic. Caroline asks her if she's ever heard of a record called the Conjure of Sacrifice, and the old woman reacts in horror.

Caroline is now convinced that Violet herself has put a spell on Ben, and that she must get Ben away from the house for the spell to be broken. She concocts a plan to drug Violet and spirit Ben away from the mansion, but Violet catches on. Caroline interrupts her before she is able to draw a magic circle around herself, and Violet passes out. Caroline gets Ben and tries to escape in her car, but Violet awakens and recites spells that keep the car from breaching the locked gates of the house grounds. As Violet emerges from the house with a shotgun, Caroline manages to hide Ben in the tool shed and she promises to return for him. She then escapes through the swamp in a rowboat. Emerging on another shore of the swamp, she hitches a ride back to New Orleans and goes to Luke's apartment, just as he gets a phone call from Violet. When Luke goes into another room, Caroline rummages through his desk and finds a skeleton key from the house, as well as a few items from the secret room in the attic. Luke suddenly appears behind her and strangles her until she is unconscious.

When she wakes up again, she is bound and gagged, and Luke is driving her back to the Devereaux mansion. Violet meets them and tells Luke not to "scratch her up any more than she already is." They force Caroline to tell them where she has hidden Ben, and when Violet goes to get him, Caroline breaks away from Luke and hides in her bedroom, where she has spread brick dust across the doorway. Using a jar of red brick dust, she begins to seal herself off in the house, covering every dooryway and blocking Luke's advances towards her, but Violet appears and smashes the jar. They struggle on the second floor of the house, and Caroline hurls Violet over a banister. She falls, breaking her legs in the process, and Caroline makes a 911 phone call to the police. Immediately afterwards, she calls Jill and tells her she is in trouble at the Devereaux mansion, but Violet has dragged herself back upstairs, and she cuts the phone cord.

Unable to leave the house yet because of Luke, and trapped on the second floor by Violet, Caroline runs into the attic. Using a schematic that she snatched away from Violet, Caroline draws a magic circle around herself, using sulfur, chalk, blood and hair. This is the circle in which the Conjure of Sacrifice takes place. Violet drags herself into the attic just as Caroline finishes the circle. Caroline feels as if she's safe in the circle, but Violet tells her "Who did you get that spell from, Caroline? Wasn't it me?" Caroline begins to feel as if they wanted her in this circle after all. Violet unveils a full length mirror and advances on Caroline with it, while Caroline says over and over "You can't hurt me, I don't believe! I don't believe!" Both Violet and Caroline scream and are knocked to the floor by some kind of explosion, which shatters the mirror as it falls on Caroline.

Afterwards, they both awaken, but Caroline now is cool and calculating and talks like Violet, because now "Violet" is in her body. The true purpose of the events have become clear: "Violet" was never really Violet to begin with, she was the spirit of Cecile in Violet Devereaux's body. Luke has similarly been taken over by Papa Justify; Ben and Violet Devereaux were simply the last host bodies that Cecile and Justify had managed to perform the "Conjure of Sacrifice" with. It seems as if the first victims of this 'transference of souls' were the two children the night of the lynching; the ritual that was being performed allowed the souls of Justify and Cecile to switch bodies with the children, who were then trapped in the bodies of Justify and Cecile and murdered. From the children, Justify and Cecile had managed to transfer to Ben and Violet. With both bodies being in old age, they set up the trap again, luring Luke into the transference and trapping his soul in the aged body of Ben Devereaux while Justify's spirit, which was occupying Ben's body all these years, transferred to Luke's young body. Caroline was intended all along to be Cecile's next host body, which explains why Cecile (in Violet's body) told Justify/Luke to "not scratch her up any more". The challenge had been to get the cynical Caroline to believe in Hoodoo.

The film ends as Caroline, now trapped in the body of Violet Devereaux, is loaded into an ambulance with "Ben", who is really Luke inside Ben's body. They are to be taken away to hospice care to die, both of them unable to speak and unable to communicate to anybody what has happened to them. Jill, who is responding to Caroline's desperate phone call, arrives at the mansion in time to see them taken away on stretchers. Caroline (in Violet's body) looks on in desperation at Jill, wanting to tell her what happened but hexed into being mute. Justify and Cecile, now housed in the young bodies of Caroline and Luke, send Jill along with them in the ambulance.