Ten-year-old Danielle Randall is at home playing with her collection of dolls as her parents Pete and Ellen prepare to go out for the night. The babysitting agency sends a new babysitter, Miranda Evans, over to take care of Danielle. Danielle comes downstairs to meet Miranda, who says that she's hoping to make child development her career so she's working as a babysitter. Ellen shows Miranda around the house and assures her that Danielle won't be any problem, and then gives the babysitter a notebook with all of Danielle's allergies, dietary requirements, and phobias neatly documented.
Once the Randalls leave, Danielle takes Miranda up to her room and shows the babysitter her prized collection of Barbie-like dolls, all kept in a cabinet with a glass front. The case is closed and Danielle insists that the dolls can't be played with. When Miranda turns to look around, there's a sound from the case and she turns around to see that one of the dolls has fallen off its stand and is leaning against the glass. The babysitter tries to open the case but discovers that it's locked. Danielle reluctantly agrees to unlock it and gets the key, but when she props the doll back up, it pricks her finger. The girl insists that the doll bit her, but Miranda tells her that she's imagining things and takes her to the bathroom to bandage the cut.
As Miranda cleans the cut, Danielle says that the doll, Shelley, is mad at her because Miranda is there and Danielle won't play with the doll anymore. She talks about how she had a friend once but she moved away. Now Shelley gets mad at Danielle when she won't play with her. Miranda offers to make hot cocoa and popcorn downstairs and Danielle eagerly agrees. However, when she warns that her mother doesn't let her have sugar that time of the night, Miranda says that it's a special occasion and they should celebrate.
Downstairs, Danielle goes on about how her dolls like TV shows and food, including how two TV characters should get hooked up. Miranda is surprised that Danielle knows that much about the real world and is watching shows like that. Danielle goes back to her room to get a game they can play, and Miranda highlights a section in her child development textbook about gift children who suffer from anti-social behavior. She's interrupted when Danielle screams for help. Miranda runs upstairs and Danielle shows her that the Shelley doll is gone. The girl insists that the doll escaped and blames Miranda for leaving the key in the lock. Miranda agrees to help Danielle look for the doll and goes to lock the case, but discovers that the key isn't there. Danielle insists that Shelley took it, but Miranda doesn't believe her.
Danielle suggests that they look in her parents' room first since it's dark in there and Shelley likes the dark. Miranda goes in and finds nothing, but they hear something break in the kitchen. They go downstairs and discover that someone has broken a cocoa mug. Danielle insists that Shelley doesn't like chocolate and insists that she loves the doll, and doesn't understand why she's mad at her. Miranda tells Danielle that she's just trying to get attention and is causing the incidents herself, but the girl insists that Shelley is the one responsible. The babysitter wonders if something broke before and Danielle blamed it on the dolls, and the girl admits that Shelley got out once before and broke her mother's teapot. Now she locks the dolls up to keep them safe.
When she realizes that Miranda thinks she's imagining things, Danielle angrily walks out of the kitchen. She trips on the Shelley doll, cutting her arm, and Danielle accuses it of tripping her. Miranda calls Ellen to ask where the first aid kit is but assures the mother that everything is fine. Danielle says that they have to put the doll back in the case, but when they take it upstairs, all of the other dolls have disappeared. The girl warns Miranda that the dolls have never escaped before and that now they're in danger.
Miranda finally has enough of what she thinks are Danielle's games. She leads the girl downstairs only to discover that the dolls are sitting on the stairs. Stepping over them, Miranda and Danielle discover that the other dolls are sitting in the living room on the furniture. A vase falls off a high shelf and Danielle warns Miranda just in time. When Miranda looks up, she sees the Shelley doll, her arms extended. There's a bracelet among the vase pieces and Danielle picks it up, warily saying that it's hers even though it looks too adult for a ten-year-old girl. Realizing that Danielle couldn't have done everything, Miranda goes to call the Randalls. However, when she glances back, she realizes that the dolls have moved while her back was turned.
As Miranda calls Ellen, the phone goes dead. When the babysitter checks the cord, she discovers that something has cut the line. She goes to get her backpack but someone has taken the battery. Danielle wanders off and Miranda sees a piece of paper pinned to the refrigerator with magnetic letters, which spell the word LEAVE. The piece of paper is a page from Miranda's textbook, talking about anti-social children.
Miranda goes to the stairs, figuring that Danielle has gone to her room. There are more dolls are on the stairs and when she walks past them, she trips on a stuffed unicorn purse. When Miranda wakes up, she's on the floor and someone is dragging her by her hair. She reaches up and discovers that three dolls are there.
Miranda grabs the unicorn and runs upstairs when Danielle screams, and finds her hiding in the closet. There are more dolls outside the door and Miranda knocks them aside and tells Danielle to let her in. The girl reluctantly does so and Miranda tells her that they have to get out of the house. Danielle insists that the dolls will get her when she comes out, but Miranda promises to carry her out so that they can't touch her.
The dolls start slamming into the closet door, while Danielle notices that Miranda has the unicorn. She tries to snatch it back and an adult woman's wallet falls out. Miranda checks it and discovers that it has a photo of a girl that looks like the Shelley doll, wearing the same bracelet that Danielle claimed was hers. Inside the wallet is a driver's license belonging to Shelley Porter. Danielle breaks into tears and says that she just wanted the other babysitters to be her friends.
As the dolls continue clawing at the door, Miranda checks through the unicorn and finds more driver's licenses, all belonging to other girls with the same names as Danielle's dolls. Danielle insists that she asked all of her babysitters to stay with her and be her friends forever, but they always left and forgot about her. Miranda realizes that the dolls were trying to warn her, not hurt her, and Danielle grabs Miranda and begs her not to stay. As the girl clutches at Miranda, there's a flash of bright light.
Later, Pete and Ellen return home and Pete calls the babysitting agency to complain that Miranda walked out and left Danielle in the closet. Meanwhile, Ellen tucks Danielle into bed and tells her that she's grounded for leaving her dolls lying around. Once she puts the dolls back in the cabinet and leaves, Danielle tells her dolls that she's grounding them forever because they were bad. She then takes out a new Miranda doll and puts it in the case, and tells them that they have a new friend.