In the opening of the film, the audience is introduced to Gina (Lena Headey), a successful radiologist. On the birthday of her father, John (Richard Jenkins), Gina, along with her boyfriend Stefan (Melvil Poupaud), her brother Daniel (Asier Newman) and his girlfriend Kate (Michelle Duncan) surprises John. In the middle of the dinner party, a mirror unexpectedly shatters for no apparent reason. Kate and Gina proceeded to clean the shards and discuss that mirrors breaking is a sign of bad luck. At work the next day, Gina was baffled by her assistant Anthony (Damian O'Hare) when he tells her that he saw Gina walking out of the building. Gina explains that she has been inside the whole time. On her way home however, she sees a woman who looks exactly like her driving a car identical to hers. Gina follows the woman to her flat and sees a picture of her and John inside the woman's room. A frightened Gina runs out of the building and drives her car. Seemingly disturbed at what she saw, she collides with another truck in the middle of the road. Gina awakens in a hospital with no memory of the accident. She is introduced to a therapist Dr. Robert Zachman (Ulrich Thomsen). Robert leaves her a calling card and Stefan fetches her out of the hospital. At Stefan's flat, Gina notices his mirror is missing and he explains he broke it by accident. A leakage bother's Gina in the bathroom and goes to check on it but is stopped when she notices Stefan's odd behavior. Gina contacts Robert about this but only attempts to admit her to the hospital again. She is advised by Robert to visit her wrecked car in hopes that she remembers anything. She does so but only finds the picture of her and John in the car. She visits John and shows him the picture. He began worrying about what has gotten into his daughter's mind. Meanwhile, at their home, Kate arrives only to find out that Daniel is not there. She takes a shower and is disturbed by the sound of a mirror breaking. Suddenly, a woman who looks exactly like her enters the bathroom and murders Kate by shoving her entire hand in Kate's mouth.Soon, Gina phones Stefan to check on him but he does not answer. She goes back to Stefan's flat to find it deserted. She hears the leakage once more and determined to see what it was, she sees Stefan, who has been dead all along, with his head smashed onto the pipe. Suddenly, the man who looks exactly like Stefan began to attack her but she escapes. Panicking, Gina calls John for help but they are disconnected when a man who looks like John appears from behind him. Sounds of shattering glass are heard. Thinking their father is in danger, Gina phones Daniel, who just arrived in their flat. Gina explains everything to Daniel about the woman who looks like her whom she saw before the accident and Gina following the woman to her flat. Daniel realizes that Gina followed the woman in her own home. Gina ends the call and goes back to the woman's flat. Daniel hears scrubbing noises in the bathroom only to see the look alike of Kate. Gina arrives in her flat and saw her own dead body in the bathroom. Gina finally comes to a conclusion:The mirror breaking at John's party released evil entities that take the exact form of their victims, kills them and continues their lives. On the moment before her accident, the evil Gina spots the real Gina driving to her flat. The evil Gina follows and kills the real Gina and escapes only to be involved in a car accident that takes a piece of the evil Gina's memory, making her temporarily good.When the evil Gina's memory finally comes back, she exits the bathroom with an expressionless face and sees the now evil John, standing outside the building.The film ends when the evil Gina, now continuing with her life as a radiologist again, ends her day at work when she stumbles upon Daniel, who escaped a presumed attack from his evil doppelganger. Daniel looks at Gina as if examining her if she was real or the evil one. Gina eerily stares and smiles at him making Daniel run away from her. The evil Gina is then seen driving her car and smiling eerily.
Output: Question: What does Gina see in the doppelganger's apartment ?, Answer: A picture of her and John