Plot
- Wales, March 15, 1984
A surrogate mother, Amelia, is giving birth in a run-down medical facility. A cloaked person, a doctor, and a military soldier are seen assisting with the pregnancy. After the birth, the cloaked figure gives the doctor and the soldier "double" monetary compensation for the complications that occurred during birth.
Amelia is surprised to discover that she gave birth to two babies instead of the single one she was expecting. She announces her plans to separate the two children so that "they" do not find out about the double birth.
- 29 Years Later and an Ocean Away
Sarah Manning sits on a subway train, staring at a picture of her daughter, Kira. She wonders if Kira has forgotten about her in the time that she has been away.
Sarah steps off of the train and notices a woman crying and acting frantic on the train platform. Sarah approaches her; and, as she does so, the woman turns around. The two women look identical. Sarah is shocked as the woman steps in front of an oncoming train and is killed instantly. Sarah steals the woman's purse, which she left behind on the train platform, as she sees it as an opportunity to turn her life around.
Sarah meets with her foster brother, Felix, at a bar; and she recalls the scene she just witnessed at the train station.
- Sarah remembers protecting Felix when the two were younger and still active in the foster system.
Sarah shows Felix the woman's driver's license as a way to prove the resemblance between the two women. Felix reveals that the woman's name was Elizabeth Childs. Sarah divulges her plan to visit Elizabeth's home.
- Sarah and Felix as children stand in front of their final, permanent foster mother, Siobhan "Mrs. S" Sadler.
As Sarah walks to Beth's apartment, she is stopped by one of Beth's neighbors who asks her how Paul is doing. As Sarah speaks, the neighbor notices her harsh personality and is confused by her British accent. Sarah states that she has family in town visiting from London.
Sarah explores Beth's apartment and questions the reasons behind her suicide.
- Beth cries in her bed, strokes a picture of her and her boyfriend, Paul, and confirms a bank deposit with someone over the phone.
Sarah discover's Beth's $75,000 bank deposit and concocts a plan to con the bank so that she can start a better life with Felix and Kira. She perfects her accent, colors her hair, and dresses up to visit the bank. While she is there, the director asks if she would like to access her safety deposit box. Sarah agrees and discovers birth certificates inside the box.
- Sarah leaves Kira with Mrs. S and Felix as she is taken away by Victor "Vic" Schmidt, her ex-boyfriend.
As Sarah returns to Beth's apartment, Detective Arthur "Art" Bell convinces her to go with him to the police station.
- Siobhan visits a teenage Sarah in jail, who was arrested after impersonating a duchess. Mrs. S is disappointed in her for getting caught.
Lieutenant Gavin Hardcastle escorts Sarah into a conference room where she is to recall the events that lead to the shooting death of a civilian woman named Margaret Chen. Sarah drinks hand soap, becomes sick, and is sent home.
Back at the flat, Sarah finds a video that Beth had recorded. Beth is concerned because she does not know who the enemy is and she no longer knows who she can trust. She states that she will never be able to trust Paul, or anyone else again. She reveals that there are already too many bodies and that she can't tell her "sisters" about the murders until she knows for sure.
- A young Sarah is ambivalent about her place in Mrs. S's foster family. Siobhan attempts to reassure Sarah that she will not be sent away to another family again.
Earlier, Felix had positively identified the body found under the train as Sarah, so that Sarah could successfully assume Beth's identity and take over her life. Felix reveals that Vic wants a funeral, but Sarah is against it because she does not want Kira to think that her mother is dead.
- Elizabeth Childs contemplates taking a handful of pills, but hides in her closet to weep instead.
Sarah showers and is in the process of changing her clothes when Paul arrives home from his business trip. He confronts "Beth" about the police hearing and starts to become suspicious of her. Sarah begins kissing Paul to distract him.
- Beth and Paul practice shooting at a gun range, they run a marathon together, and they sleep together passionately in their bed. Later, Beth becomes suspicious of Paul, discovers letters that he has hidden, follows him as he sneaks around conspicuously, and the two are separated by an emotional barrier when they sleep.
Sarah cries as she witnesses the funeral that Vic has arranged for her. As she goes back to her car, she is followed by Katja Obinger, a red-haired woman who also shares a striking resemblance. Someone watches the two women from afar.
Katja gets into Sarah's car and recites a riddle in order to elicit a response from the woman she believes is Beth.
- Beth is on the phone and devises the riddle as a way for each of the look-alikes to identify each other.
Sarah does not know how to respond to the riddle, and Katja realizes that she is not Beth. Katja is suddenly shot by a sniper through the car's windshield, and Sarah flees the scene as Beth's pink phone rings in the background.
Helena, yet another woman who looks like Sarah, leaves the grassy area on a motor cycle with a sniper rifle in tow. She vows to enact her revenge against Beth for murdering Maggie Chen.
