Orphan (2009)

In Hamden, Connecticut, Kate and John Coleman's marriage is strained after the stillbirth of their third child, Jessica, whose loss is particularly hard on Kate, a recovering alcoholic. She and John then decide to adopt a 9-year-old Russian girl, Esther, from St. Mariana's Home for Girls, a local orphanage. Their 6-year-old deaf daughter, Max, embraces Esther, but their 12-year-old son, Daniel, is far less welcoming.

One night, Kate and John begin to have sex until Esther interrupts them. Kate becomes suspicious when Esther expresses far more knowledge of sex than expected of a child her age. Esther then exhibits hostile behavior in front of Max and Daniel, such as killing an injured pigeon and breaking the ankle of a bullying classmate named Brenda. Sister Abigail, the head of the orphanage, visits the household, warning Kate and John that tragic events and incidents occur around Esther, including the house fire that killed her previous adoptive family. When Abigail attempts to leave, Esther causes her to crash her car on the road and then bludgeons her to death with a hammer. She forces Max to help her move the body and then hides the evidence in Daniel's treehouse. Daniel sees them at the treehouse, and later that night, Esther interrogates him about what he saw, threatening to castrate him if he tells his parents.

As Kate becomes further convinced about Esther's unusual behavior, John believes she is being paranoid and tells Esther to do something nice for Kate. Esther rips out the flowers from Jessica's grave and gives them to Kate as a bouquet. Kate is horrified and grabs Esther's arm in distress, asserting that she did this on purpose. That night, Esther breaks her own arm with a vice, and falsely blames Kate, causing further strife in Kate and John's marriage. The next day, Esther releases the brake in the car, causing it to roll into oncoming traffic with Max inside. She also points out the wine she found in the kitchen, causing John and Kate's therapist to suggest Kate return to rehab, with John threatening to leave her and take the children if she refuses. Kate discovers that Esther came from a mental hospital named the Saarne Institute, and the orphanage she claims she was from has no record of her.

When Daniel learns about Sister Abigail's death from Max and searches the treehouse, Esther, having heard their conversation last night, sets it on fire with him inside. He falls from the treehouse while trying to escape, causing him to fall unconscious from the impact. Esther uses this opportunity to try to kill him, but is thwarted by Max. Daniel is seriously injured, and while in the ICU in the hospital, Esther tries to asphyxiate him, stopping his heart, but the doctors come in time to revive him. Kate, enraged about what happened and believing Esther was involved, slaps her before being restrained and sedated. That night, Esther dresses provocatively and attempts to seduce John, and after realizing that Kate was right about her, he angrily threatens to send her back to the orphanage. At the hospital, Kate is contacted by Dr. Värava of the Saarne Institute and learns that Esther is actually a 33-year-old Estonian woman named Leena Klammer. She has hypopituitarism, a rare hormonal disorder that stunted her physical growth and caused proportional dwarfism, and she has spent most of her life posing as a little girl. He states that she has killed at least seven people and was one of the institute's most violent inmates, being kept restrained at all times. She also tricked a family in Estonia into adopting her, and when she failed to seduce the father, she killed him and the rest of the family, burning the house down to destroy the evidence.

While Kate is talking to Dr. Värava, Leena furiously removes her makeup that makes her look childlike; the ribbons she wears around her neck and wrists conceal the livid scars she received from trying to break out of her restraints. She also removes her prosthetic childlike teeth, revealing her real, rotting teeth, and destroys her room. When the power goes out and Leena disappears, John enters her room and uses the aquarium blacklight to find her hidden, violent paintings. After tearing them off the wall, he discovers pornographic images resembling himself and Leena painted on the walls. She then attacks him downstairs and stabs him to death.

Kate rushes home and, after finding John's body, searches the house desperately to find Max. Leena attempts to shoot her, wounding her arm. After Leena opens fire on Max in the greenhouse, Kate breaks through the greenhouse roof and knocks her unconscious by landing on her. Kate and Max flee as police arrive, but Leena attacks them near the frozen pond, hurling them onto the ice. As the two women engage in a violent struggle, Max tries to shoot Leena herself but misses, hitting and shattering the ice and causing her and Kate to be sent underwater. Kate begins to climb out with Leena clinging to her legs. Leena reverts to her Esther persona, begging "Mommy" not to let her die, while hiding the knife behind her back. Kate retorts angrily that she is not Leena's mother and kills her by kicking her in the face, snapping her neck and sinking her body. Kate and Max are met by police.