Case 39 (2009)

Emily Jenkins (Renée Zellweger) is a social worker living in Oregon who is assigned to investigate the family of Lillith Sullivan (Jodelle Ferland), a troubled ten-year-old whose school grades have declined due to an emotional rift with her parents, Edward and Margaret Sullivan (Callum Keith Rennie and Kerry O'Malley). Emily suspects that the parents have been abusing Lillith for her lack of obedience and begins to investigate the family further, questioning Lillith about her parents and planning a visit at the family's home. When Lillith is interviewed by Emily's boss and is too intimidated to answer his questions honestly, Emily visits Lillith at her school and gives the girl her home phone number, telling her to call if she is being hurt or needs help.

Her suspicion is later confirmed when Lillith calls Emily in the middle of the night, informing her that her parents are coming to kill her. With the help of Detective Mike Barron (Ian McShane), Emily intercepts and captures Edward and Margaret before they can incinerate Lillith by trapping her in their home oven and baking her alive.

Lillith is originally going to be sent to the children's home, but she begs Emily to look after her instead, and with the agreement of the board, Emily is assigned to take care of Lillith until a suitable foster family comes along. Two weeks after Lillith moves in with Emily, a boy named Diego (Alexander Conti), another one of Emily's cases, brutally murders his parents in the middle of the night, and Detective Barron informs Emily that somebody phoned Diego the night before the crime, and that the call originated from her home.

As she is suspected of involvement in the incident, Lillith undergoes a psychiatric evaluation by Emily's best friend, Douglas J. Ames (Bradley Cooper). However, during the session, Lillith asks Douglas what his fears are and begins to subtly threaten him by turning the questions around and beginning to evaluate him. Douglas conveys his discomfort to Emily and says that he will call a specialist in the morning to help with Lillith's evaluation. During the night Douglas receives a strange phone call at his home. A mass of hornets, which Douglas had previously told Lillith that he was afraid of, begin to fly out of his body, and he grows hysterical and kills himself.

After speaking to Diego and attending Douglas' funeral Emily becomes more suspicious of Lillith than her parents, and visits the asylum where Edward and Margaret are being kept under custody for their attempted murder of Lillith. Margaret is hysterical and unable to see visitors but Edward reveals to her that Lillith is far from human and is actually a Succubus-like demon who feeds on emotion, and is capable of causing deadly hallucinations based on her victims' fears. Their attempt to kill her had been an attempt to save themselves and others, and that she is now feeding off of Emily's kindness and goodness and that Lillith will bleed her dry before moving on to her next victim.

Edward also informs Emily that the only way to kill Lillith is to get her to sleep, which she rarely does. Shortly after Emily leaves the asylum Margaret hallucinates that she is on fire and Edward is stabbed in the eye after attacking a fellow inmate who spoke to him in the voice of Lillith. After Detective Barron receives a strange phone call in his home from Lillith he arms himself to help Emily. However, as he is on his way to Emily, Lilith makes him hallucinate that he is being attacked by dogs and he fatally shoots himself in the head with his shotgun.

After realizing that her closest colleagues have been eliminated and that the rest of her cases will be next, Emily serves Lillith tea spiked with a sedative and waits for her to fall asleep. While Lillith is asleep, Emily douses her home in gasoline and sets it ablaze, hoping to kill Lilith. However, Lillith, upon discovering Emily's plot, escapes unharmed.

A police officer offers to escort Emily and Lilith to a temporary place to sleep but as Emily is following the police cars, she suddenly takes a different route. Driving recklessly and at a high speed, to scare Lillith, the girl forces Emily to relive her childhood memory of her mother driving fast in a rainstorm and a truck overturning in their path. Emily fights the memory, telling herself that it is not real and the image fades, leaving Lillith herself confused that her illusions no longer scare Emily.

Emily crashes through a gate and drives the car off a pier into a lake. As the car sinks, Emily struggles to lock Lilith (now in full demon form) in the trunk by folding the rear seats back against her and drowning her. Emily exits the car and swims away but Lilith grabs her leg through a hole in the car's tail light section. Eventually Emily breaks free and Lilith lets go as the car continues to sink. Emily climbs back ashore and watches the water to assure she is really gone. The film ends with Emily smiling, relieved to finally be rid of Lilith.