Jenny is out of the hospital yet again with no mention of the time that she went crazy and pretended that she was Mr. Hagen. She's now in therapy with Dr. Morton and telling him about the dreams that she still has. She also moved to a new house with her mom who has a new boyfriend named Winston.
After her latest session, she heads to the mall with her best friend Claire and her friend's new boyfriend Rick. She runs into Cal and reveals that they're still seeing each other. He apparently stood by her side and wrote her letters when she was in a mental hospital. A few days later, she plans to sit outside, read a book, and relax, but she meets her new neighbor.
Mrs. Warsaw is a single mother with three kids: Meredith and twins Seth and Sean. The two twins conveniently look like just like a little white-haired boy she saw outside in the middle of the night. She asks Jenny to watch her kids for a few minutes while she runs to the store, and she reluctantly agrees. The kids all seem pretty good, but she notices that Sean is a little mean.
After sitting for the kids, Jenny swears that she feels an icy cold hand touch her back. She tries to ignore it, but she feels the same thing happen a few more times. It eve happens when she's on the phone with Cal, but she tries to ignore it. Mrs. Warsaw then asks her to babysit for her one night, and her mom isn't so sure it's a good idea, which is ironic given that she made Jenny take a sitting job in one of the other books.
The kids all fight and act like little asses, and Jenny hears a strange noise coming from the attic. She asks the kids about it, and they tell her that they always hear weird things coming from up there. Jenny tries to check out the attic herself, but the door is locked and the kids say that their mom always makes sure that it's locked. After putting the kids to bed, she hears noises again, checks out the twins' room, and realizes that they're missing. No worries though, they were just playing a joke on her. She tells them that if they don't stop scaring her, she'll stop sitting for them.
She clearly shouldn't be sitting for anyone but she keeps doing it. The next time she's over at the house, she hears a voice talking in her ear that warns her to leave or she'll die too. She then hears the sound of glass breaking and finds that Cal sneaked into the house. While on the phone earlier, she screamed and hung up, and he was worried about her. Cut to a few more weird times, and she decides not to sit anymore.
Jenny wakes up in the middle of the night to weird noises in the house and sees a little white-haired boy running through her yard. Her mom tells her that there's been a prowler vandalizing the neighborhood lately and that she didn't tell her because she didn't want to worry her. She offers to call the police, but Jenny asks her not to. Claire picks up on her feelings and offers to help her sit, but she once again says that she's done babysitting.
Then Mrs. Warsaw calls with an emergency. Her sister is in the hospital and she needs someone to sit for her right away. Jenny reluctantly agrees and goes over to the house. Seth isn't around for awhile, so she starts to cut up a cake to give the kids dessert. The knife suddenly attacks her and tries to stab her in the chest. The kids pop up, and she notices a weird look on Seth's face. Sean then comes to her later that night and says that he wants to tell her a secret. Seth interrupts them, Sean gets freaked out, and he leaves without telling her anything.
She ends up telling Claire about the knife incident, and Claire tells her mom. Mrs. Jeffers suggests that maybe she isn't quite well, which leads to a fight. Jenny then goes back to the Warsaw house and sits for them again. This time, she hears the weird voice again after the kids go to sleep. The voice threatens to kill her, and she runs through the house looking for a place to hide.
Jenny ends up in the bathroom and sees a little boy staring back at her from the mirror. She thinks that it's Seth, and the voice tells her that it's time for her to die. The voice keeps talking to her until she grabs a vase and throws it through the mirror. Mrs. Warsaw comes home and finds her covered in blood and rushes her home. Jenny keeps mumbling about the twins, and Mrs. Warsaw reveals that she doesn't have twins.
After they put her to bed, she wakes up and listens to them talk. Mrs. Warsaw says that the real estate agent told her that a little boy was murdered by his babysitter in her house, and Mrs. Jeffers says that maybe it was too soon for Jenny to start sitting again. You think? She then looks out the window and sees a young woman standing in the attic of the Warsaw house. The woman asks for help, and Jenny agrees to help her.
Just as she gets to the attic door, Seth appears and begs her not to open it. He tells her that Monica, his sitter, killed him and that he made himself look like Sean because he always wanted a brother. He starts crying and grabs her, but she opens the door anyway. Sean screams that the sitter will kill her, and the sitter does grab her and carry her, but she stops and puts Jenny down before attacking Sean.
Suddenly, her mom and Cal are in the house. Her mom was so worried when she couldn't find her that she called Cal, and they both rushed over there. Jenny tells them that she's fine and that everything will be fine from now on. At the end of the book, she even says that maybe she'll babysit again someday.