Now with both of her parents dead, NAOMI returns to her childhood home with the intention of recollecting items before her AUNT EDITH, the owner, sells the house. TESSA visits the house, telling her that she was close to her parents. Although she’s bewildered by her at first, Naomi takes kindly to Tessa whom she sees as an opportunity to get to know what her parents were like before their death, since she hardly got to see them.
But one day, Tessa claims to be Naomi’s long lost older sister. Naomi doesn’t believe her and Tessa lashes out. She leaves the house but returns that night, breaking in. Naomi confronts Tessa and attempts to escape, but both women injure each other. They decide to call a truce where Tessa reveals what she wants: She wants Edith to officially recognize her as part of the family and to take the house herself. If Naomi doesn’t help her, she will kill her as well as Edith and her sister Ashlynn. Naomi accepts and calls Edith, who denies that Tessa is part of the family. But as they argue, Tessa reveals that Edith and Naomi’s parents psychologically and physically abused her over the years. This prompts Naomi to confront Edith about how abusive she was to her. Edith believes that this home invasion is a sham concocted by Naomi and Tessa so they can keep the house. She tries to leave but Tessa kills her.
Tessa tells Naomi that now she has to help her hide the body and clean after the house. She turns her down but agrees when Tessa tells her she could still murder Ashlynn. They hide Edith’s body and now Tessa says that the house is effectively theirs now, and that she won’t let Naomi go. She will attempt to build the sisterly bond she’s wanted for years. Tessa falls asleep and Naomi sneaks away to call Ashlynn and tell her what’s happening, but Tessa catches her and locks her in the basement. Ashlynn comes in and fights with Naomi in order to free Naomi. She succeeds and both escape, but Tessa injures Ashlynn in the struggle. As they’re on the way out, LAVINIA, a young girl appears out on the road, stopping the car. She injects Naomi with a tranquilizer.
Naomi wakes up, realizing that Lavinia is Tessa’s daughter. She attempts to escape and ends up knocking down the chlorine and alcohol they used to clean the murder scene. In the confrontation, Tessa is blinded by the chlorine. Naomi starts a fire by knocking down a set of candles, and escapes with Lavinia in her arms. Months go by, and a recovering Ashlynn and Naomi look on at the house. Naomi tells Ashlynn that she believes Tessa, including everything she said about her parents but that doesn’t mean that she can’t love them. They go to the cemetery to leave flowers along with Lavinia, but Lavinia acts coldly toward Naomi, still angry that she killed her mother.