The movie opens with Caroline Ellis (Kate Hudson) reading a story to an old man. She is a nurse at an old peoples hospital in New Orleans. As Caroline finishes the story, we see that old man slowly pass away. Caroline shuts the book and gets up to alert one of the on staff nurses. Caroline gathers up all the personal items that the old man left behind and puts them in a box with his name on it. Hours later, we see Caroline sitting in the waiting room. The old man's family called in and said that they don't want his belongings. One of the nurses tells Caroline to discard of the personal items box. Caroline takes the box outside and opens the dumpster. We see other boxes that hold personal items thrown away in the dumpster.

Cut to Caroline reading a newspaper on a train. She sees that an old woman is seeking an in-home hospice caregiver to care for her dying husband. This means Caroline would have to live in the mansion and run into town every now in then. Caroline circles the ad in the paper. We next see Caroline at a bar with her best friend Jill (Joy Bryant). Caroline tells Jill how she quit working as a nurse at the old peoples home, and is going to be starting her new job as an in home caregiver at a mansion located in Terrebonne Parish. Caroline says her interview for the job is tomorrow. Jill says that Terrebonne Parish is the swamps and only people with three teeth live there. Caroline explains how she's 25 years old and wants a little change in her life.

The next day, Caroline arrives at the mansion. Swamps surround the mansion and it's pretty rundown yet still classy looking. Caroline knocks on the door a few times and no answers. She lets herself in and closes the door behind her. As she closes the door, we see a religious statue standing right there that is pretty creepy. Just warning you, every time you see the statue in the movie you'll jump. She's greeted by the family lawyer, Luke (Peter Saarsgard). They chat and he tells her that Caroline is the 5th in-home caregiver that will be working here. The reason why all the other girls left is because they didn't like the location.

Luke takes Caroline outback and is introduced to Violet Devereaux (Gena Rowlands). Violet refuses to say hi to Caroline and gives her an attitude. Caroline is then introduced to Ben (John Hurt). Ben is in a wheelchair; he had a stroke and is paralyzed. He can't talk and can barely move. It happened about a month ago, up in the attic. Violet goes back up to Caroline and explains that Caroline isn't right for the job, that she simply wont understand the house since Caroline isn't from around here. Caroline says she's from New Jersey. Violet waves her hand at her. Caroline figures that since Violet will have an attitude towards her, then she doesn't want to work for her. Caroline goes back to her car and gets ready to leave. Luke chases her out and says that Violet really is a sweet woman and tells Caroline not to take anything personally. Ben having a stroke has been really hard on Violet.

Caroline understands and eventually she gets the job. The next morning, Caroline goes back to Jill and they say their goodbyes. Caroline drives back to the mansion. On the way she notices that her gaslight has gone on. She finds a rundown gas station. She fills up, and goes inside to pay. As Caroline walks in, she notices a red colored dust is by the door. She also notices chicken bones and other voodoo like items hung all over the walls. Caroline eventually finds an old woman with white eyes (she is blind...she's extremely creepy looking). She pays and heads to the mansion.

As she arrives at the mansion, Violet shows Caroline to her room. Violet gives Caroline a Skeleton Key, which will open every door. There are 30 rooms in all. Caroline goes in her room to pack. She notices a spot on the wall were a mirror once was. She goes back to Violet and the two talk some more. Caroline notices another spot on the wall where a mirror once was. "Was there a mirror here once? I've noticed in the rooms and bathrooms that there aren't any mirrors" Violet nods her head and says that all the mirrors have been put away. She claims the reason why no mirrors are in the house, is because she doesn't like to look at herself because she is old.

Later on, Caroline goes to Ben's room. She tucks him into bed. Ben grabs her hand and doesn't let go. Caroline eventually gets Ben to let go and Violet walks in. She says it 5 pm so its time for Ben to take his medicine.

That night, Caroline puts Ben to sleep and says goodnight to Violet. Caroline goes to bed. Late that night, she is woken up by loud banging noises. She gets up out of bed and checks on Ben, who is missing from his room. She notices that the window is open. She sticks her head out and sees Ben climbing along the roof. She calls out for him but its no use. Ben eventually slips on the roof, due to the heavy rain, and falls to the ground landing on a pile of leaves. Caroline runs to alert Violet, and then goes to Ben. The two help Ben, and Violet tells Caroline to get his wheelchair. Caroline runs back to Ben's room and gets the wheelchair. On her way out, she notices potted plants are all knocked over along the bed. She picks up one of Ben's white bed sheets and finds the word 'HELP ME' written in soil. She takes the bed sheet and stuffs it in her room's closet. Caroline gets the wheelchair to Ben and he is ok.

The next morning, Caroline and Violet are in the garden. Caroline asks Violet how Ben had his stoke. Violet says she doesn't know. Just before Caroline asks another question, Violet speaks out and asks Caroline to get her some gardening supplies up in the attic. Caroline goes up the attic and opens the door. She finds the gardening box. On her way out she notices a door located in the back of the attic. A large shelf is blocking it. Caroline manages to make her way through the shelf and attempts to open the door. She sticks her key in, and out pops a small piece of metal. The small piece looks like it belongs to another skeleton key (You'll find out later). She attempts to open the door again and it works. She makes her way into this hidden room. She finds all voodoo type items. Monkey heads, bones hanging from the ceiling, jars filled with human organs, etc.

Caroline comes across a shelf holding all boxes. She looks in one of the boxes and finds old vinyl records. She takes one particular record out and reads the label. It's a sacrifice spell. Violet calls out Caroline's name and goes up to the attic. Caroline hides. As she is hiding, she bumps into a mirror covered with a sheet. She also finds about 5 other mirrors covered with sheets. Caroline hides behind a mirror just as Violet walks into the attic. Violet leaves the attic and Caroline takes the sacrifice vinyl record with her.

Later on that day, Caroline and Violet meet up in the garden. Caroline asks once again what happened to Ben. Violet realizes she has to come clean with Caroline. Violet explains that many years ago a banker who had a wife and two children owned the house. The banker and his wife had two black servants, referred to as Papa Justify and Mama Cecile. Papa and Mama where like the local witch doctors and able to heal and do things with magic similar to voodoo. To be more specific it's actually called Hoodoo. Hoodoo is like Voodoo, but Hoodoo is more of a magic practice. The banker and his wife mistreated Mama and Papa but they did not complain or rebel against them. On the night of a big party at the mansion, the banker and his wife were working their way through the guests being the perfect hosts as usual but soon realized they could not see their two children anymore. They looked everywhere and got the party guests to look as well. They went into the loft and found Mama and Papa standing over their two children who were sat in chalk and sand circle, surrounded by candles and mirrors. The children looked fine but Mama and Papa were in the grip of a seizure. The party guests immediately turned on Mama and Papa, even though the children said it was they who asked to be taught about the magic. The party guests dragged the terrified Mama and Papa outside and immediately hung and burnt them alive. Their spirits were still said to be in the house, in that attic room where they kept their magic. Ben was in the attic and saw Mama and Papa, and they paralyzed him and took his speech.

The reason why there aren't any mirrors in the house, is because Violet claims that you can see the servants' spirits in the mirrors. She believes spirits are in her house.

Next we see Caroline giving Ben a bath. She takes one of her own pocket mirrors and says out loud that spirits can be seen in the mirrors. She takes the mirror and puts it up to Ben's face. Ben freaks out and slaps the mirror out of Caroline's Hand. Caroline apologizes to Ben.

That night, we see Caroline and Jill at a local bar. Caroline explains to Jill that she thinks Violet hurt Ben. She doesn't believe in any of that magic crap. Jill brings up that Hoodoo, like Voodoo is popular around this area. (Once again, Hoodoo is a magic practice). Jill says that if you believe, you can pretty much be a god of power. Luckily, Hoodoo can't hurt you if you don't believe in it.

Jill says that her aunt owns a hidden Hoodoo shop located in the back of a laundry place downtown. Later that night, we see Caroline sleeping in her bed tossing and turning. She is seeing flashes of Mama and Papa. Caroline sits up in bed and we see Caroline's face all stitched up with black thread around the eyes and mouth (This scene scared me the most). Caroline then wakes up and realized it was just a dream. Caroline gets in her car. Violet chases her outside and asks where Caroline is going. Caroline replies "Just out"

Caroline goes down to the Hoodoo shop. She goes up to the owner (Jill's aunt) and tells her about Ben's symptoms. She explains that she thinks Ben believes magic did this to him, so it's all in his head. The owner makes up a magic kit for Caroline and gives it to her. On her way out, Caroline asks what the red dust at the doorway is. The owner says it's Brick dust. Nobody that means you harm can cross it. You lay a line down; it's how you tell whom the enemies are.

After the Hoodoo shop, Caroline goes to meet up with Luke. She says that she thinks Violet Hurt Ben. She explains to Luke that Ben shouldn't be in that house with Violet anymore. She thinks Violet is just over medicating him and she is a threat to him. Luke says he really doesn't know what to believe. Caroline remembers the gas station where the old creepy blind lady lives. Her and Luke head to the gas station and meet up with the blind lady. They talk about Hoodoo. Caroline mentions the sacrifice vinyl record she found up in the attic. The blind lady starts to get nervous and says she has heard the record before. The record is evil.

That night, Violet fell asleep while watching TV. Caroline goes up to Ben's room and starts the magic spell, believing that, if Ben believes magic did this to him, he may believe magic will undo it. Part way through the spell, Violet can be heard in the distance calling out for Caroline. Caroline ignores her and Ben starts to twitch, his arms start to relax and his posture is less stiff. Violet is getting closer. Ben tries to talk, asking for help. Caroline asks him why he needs help as she hurriedly hides the magic kit as Violet is close now. Just as Caroline hides the kit, Ben points to the doorway. Violet is standing there. Caroline says she was just making Ben comfortable but is now convinced that Violet is trying to harm Ben. She is also alarmed that the magic seemed to have worked.

Later on, Violet is making dinner for herself and Caroline. Caroline wanders off into one of the rooms and lays a line of brick dust along the doorway. Caroline calls for Violet. Violet comes and stands at the doorway. Caroline asks Violet to come in because she has to show her the leak in the roof. Violet refuses because she is in the middle of making dinner. Violet then takes something out of her pocket and tells Caroline to come and get it. Caroline sticks out her arm and says "Ok come inside this room and give it to me". Violet puts the objects back into her pocket, smiles and calls Caroline a funny young girl. Caroline is now convinced Ben is in real danger from Violet and decides she will try to rescue Ben.

Violet calls Caroline for dinner and Caroline runs into the bathroom. She injects some type of medicine into some sugar cubes. The medicine will put Violet to sleep for a little while. The two meet at the table and Caroline passes the sugar cubes to Violet. Violet refuses and says she doesn't want sugar in her tea this time. Violet gets up from the table and goes into the kitchen to get something.

Caroline slips something into Violets drink and Violet passes out. Caroline gets Ben downstairs and into her car but the gates are sealed. She backs up her car and tells Ben to hang on tight. She rams into the gate but the gate is still sealed. Violet wakes up and gets her shotgun. Caroline gets Ben out of the car and hides him in the tool shed. She tells him she is going to find help and will be back. Violet shoots at Caroline but misses. Caroline gets in a rowboat and heads down the swamp.

In the distance, Caroline sees some headlights. She meets up with a guy, and he gives her a lift to Luke's apartment. Caroline and Luke meet up and Caroline explains that Violet tried to kill her. Luke is still cautious but he says he can help. Violet calls Luke and he wanders into another room, covering for Caroline, saying he hasn't seen her. While he's gone, Caroline looks at Luke's desk and sees legal books and the like. But under the legal books she sees pictures of her. Lots of them. She opens his desk drawer and sees magic type items, along with another skeleton key like hers but with a piece missing. She realizes that Luke is part of this. Luke appears behind Caroline and strangles her, which knocks her out.

Caroline is driven back to the house and dragged inside, her hands tied and mouth gagged. Violet tells Luke to keep the gun on her while she goes to find Ben who she releases must be somewhere nearby. Once Violet is gone Caroline runs for her room but Luke stops dead because of the red brick dust Caroline had put there earlier. She gets through the window, cuts the rope tying her and removes the gag. Violet finds Ben in the shed. Ben has a pair of scissors and attempts to hurt Violet, but he can't. Violet sees Caroline getting away, so she goes to meet up with Luke.

Caroline gets 2 jars of Brick dust and covers every doorway in the house, stopping Luke and Violet from getting to her. Eventually, Violet gets up to Caroline and the two grab and push each other. Caroline Manages to back violet up into a wall and then manages to push Violet over the stair railing. Violet hits the ground hard with two bloody and very broken knees.

Caroline runs up the attic. She sees a chalk drawn circle on the floor, along with some candles. Luke and Violet have set up some type of ritual it seems. Caroline goes over to the circle and stands in it. She picks up a magic book and finds a protection spell. Caroline adds weird types of designs to the chalk circle. Violet makes her way into the attic and confronts Caroline. Caroline says that Violet can't hurt her because the chalk circle is a protection spell. However, Violet says that the spell Caroline used to protect herself also stops Caroline from leaving the circle.

Violet says, "Wait, I thought you didn't believe in this stuff". Caroline now realizes that the protection circle is useless and she is in danger now because the protection spell is backfiring on her. Caroline shouts out that she doesn't believe. Violet takes a mirror on wheels, and pushes it onto Caroline, which knocks her out. The screen fades to black.

Seconds later we see Caroline and Violet starting to wake up at the same time. Caroline gets to her feet and walks over to Violet. She bends down and takes one of Violets thin cigars and smokes it. Luke comes in and goes up to Caroline. We see Violet's body on the floor and she is shaking in fear. I'll explain this right here. Mama was in Violet's body the whole time, and Caroline was switched into Violet's old body. The whole time, Luke was really Papa Justify and Luke was actually in Ben's body the whole time.

An ambulance comes and takes Violet and Ben's bodies away to a rest home. Jill also comes to the house and meets up with Caroline. Luke says that Violet and Ben loved Caroline so much, that they gave her the mansion.

Explanation: Mama's spirit was in Violet's body, while Papa Justify's spirit was in Luke's body. The reason why Mama wanted to switch out of Violet's body was because Violet's body was simply too old and worn out. In the end Caroline and Luke (Mama and Papa in their new young bodies) have Caroline's spirit and Luke's spirit sent into Violet and Ben's bodies and sent off to an old persons home. Back to the children a hundred years ago, Mama and Papa actually switched their spirits into the two little kid's bodies, while the kids' spirits were put into Mama and Papa's bodies. Mama and Papa's bodies were hung and killed.