A woman cries into a camera. She says she thinks they are going to kill her, and then we hear her scream for her life from behind a locked door.Cut to a nanny named Chloe, who is looking to adopt a child with her husband, Rob. The adoption agency is skeptical of the couple's family history/background. Even Rob isn't sure he wants to adopt a child. Chloe takes a break from Rob and temporarily stays with her pregnant friend, Stephanie.With no money coming in, Chloe takes a live-in nanny job with a young couple, Emily and Michael. Michael is a musician, and Emily is in fashion. They live in an adorable cottage home and have a few rules. Their child Tommy is not allowed to leave the house, Chloe must respect their privacy, and she has to use a cell phone that they supply her. The house has a lot of electronically locked doors and hidden areas. When Chloe first meets Tommy, he is hiding under a stairwell that is accessed by a secret tunnel. Apparently, he has many hiding spots. He leaves her notes and bobby pins. Chloe has to remind herself not to get too attached.Things get strange quickly. Michael installs nanny cams into teddy bears, and Emily dances in the middle of the night in the backyard by a bonfire. Tommy also has terrible night terrors that can only be tamed by a creepy song.Chloe doesn't follow the rules and takes Tommy out to a park. At the park, Chloe meets another nanny and learns that she isn't their first live-in nanny. The nanny warns Chloe to be careful because Michael and Emily are crazy... Chloe gets caught, and Emily explains why Tommy can't go outside. According to Emily, she used to work as a costume designer for a boy band. One of the band members named Baz became obsessed with her and stalked her and her family. They are keeping a low profile.Chloe and Tommy play hide and seek, and she does some more seeking than hiding. Chloe finds files on herself and previous nannies. She also notices all the windows have key locks on them. While in the basement, Tommy hears someone behind a locked door and tells Chloe. Chloe calls the police and grabs a knife. Emily pops out of nowhere and claims it was her in the basement. She reprimands her calling the police. They want to keep a low profile.Chloe visits her pregnant friend Stephanie and her cop boyfriend, Kevin. They talk about the strange occurrences and creepy people Chloe is working for.The low profile doesn't last long when the boyband comes to town, and a ticket to the concert ends up in the household. Chloe is locked in her room without her phone and is given a bucket. Emily and Michel think she is working with Baz, the boyband guy.Lifting the bedroom carpet Chole sees the word "Mattress" written in blood in the underside of the carpet. She lifts the mattress and find a teddy bear hidden inside the mattress. She pulls out a nanny cam and also finds a pen drive hidden inside the bear. She gets her iPad and watches old nanny cam footage from Sylvia, (the previous nanny.) saying she's going to get killed. Chloe realizes that she is in real trouble. She attempts to pass notes to Tommy to get her help. Stephanie stops by because she hasn't heard from Chloe in a few days. She threatens to come back with her cop boyfriend if she doesn't hear from Chloe soon.To preserve herself, Chloe makes up lies about knowing Baz from the boyband. (Learning this from watching the footage of Sylvia's where she too lied about knowing Baz to keep herself alive) She tells Emily that Baz is still in love with him and promises to get Rob to let Emily backstage for the secret concert. Later, Michael brings breakfast to Chole who says she isn't hungry. Then Michael starts looking for something and he too finds the word "Mattress"