text: The film opens in 1974, as a young girl, Dahlia, stands outside after school in the rain, waiting for her mother. Flash forward to 2005, we see a grown-up Dahlia  in the midst of a bitter mediation with ex-husband, Kyle , over custody of their daughter, Cecilia . Kyle wants Cecilia to live closer to his apartment in Jersey City, but Dahlia wants to move to Roosevelt Island, where she has found a good school. Kyle threatens to sue for full custody because he feels the distance is too great. He also claims that Dahlia is "mentally unstable." Dahlia and Cecilia see an apartment in a complex on Roosevelt Island, which is just a few blocks from Cecilia's new school. The superintendent of the dilapidated building is Mr. Veeck . The manager is Mr. Murray . During the tour, Cecilia sneaks to the roof where she finds a Hello Kitty backpack near a large water tank. They leave the bag with Veeck, and Murray promises Cecilia that she can have it if no one claims it. Cecilia, who had disliked the apartment, now desperately wants to live there. Dahlia agrees to move in. Shortly after, the bedroom ceiling begins to leak dark water. The source is the apartment above, 10F, where the Rimsky family lived up until a month ago. Dahlia enters 10F and finds it flooded, with dark water flowing from every faucet, the walls and toilet. She finds a family portrait of the former tenants—a mother, father, and a girl Cecilia's age. Dahlia complains to both Veeck and Murray about the water, but the former does little about it despite the insistence of the latter. Dahlia soon has dreams of a little girl who appears to be Cecilia returning from a visit to her father's home, but the girl's appearance changes every time Dahlia looks away, so that she looks like the girl in the portrait in 10F. Cecilia has started school, but according to her new teacher , she isn't fitting in and is spending too much time with an imaginary friend, named Natasha. A psychologist is recommended, but Dahlia declines and tells Cecilia to ignore Natasha. Although Veeck had said it was claimed, Dahlia discovers the Hello Kitty backpack in the laundry room's garbage. Cecilia later finds it in the elevator. The name in the backpack reads "Natasha Rimsky". The ceiling, shoddily patched by Veeck, leaks again. At school, Cecilia appears to get into a fight with Natasha, who appears to control her hand while painting. She's taken to the girls' bathroom where she passes out after dark water gushes from the toilets and sinks. Dahlia, who is meeting with her lawyer, can't be reached, so Kyle picks her up and takes her to his apartment. Dahlia breaks down when she can't find her daughter and has strange dreams. These lead her to the roof and up the ladder of the water tank, where she finds Natasha's body. When police arrive, they discover that Natasha's father thought she was with her mother, while the mother thought the girl was with her father. The girl was left alone in the abandoned apartment and fell into the water tank, which Veeck had left open. He was aware of her body, which was why he refused to fix the water problem plaguing the complex. Veeck is arrested and Murray is questioned. Dahlia agrees to move closer to Kyle so shared custody will go easier. As Dahlia packs, Cecilia is taking a bath. A girl in a hooded bathrobe comes out of the bathroom, wanting Dahlia to read to her. When she hears voices in the bathroom, she realizes that the girl is Natasha. Natasha begs Dahlia not to leave her, but Dahlia rushes into the bathroom to save Cecilia. Natasha then locks Cecilia in the shower compartment and holds her underwater. Dahlia pleads with Natasha, promising to be her mother forever. Natasha lets Cecilia go and floods the apartment, causing Dahlia to die from drowning. Her and Natasha's spirits are shown walking down the hallway. Kyle picks up Cecilia from the police station. Weeks later, the two go back to pick up the rest of her stuff. Cecilia has a flashback of her and her mother looking at pictures together, and in the elevator, her mother's ghost braids her hair and comforts her—telling her she will always be there. Kyle, momentarily terrified with a malfunction in the elevator, the weird behavior of his daughter, and perhaps noticing her hair had been braided, finally takes her to his apartment in Jersey City.