Forty-year old Christine Lucas (Nicole Kidman) wakes up with a man whom she doesn't know. The man calls himself Ben (Colin Firth), her husband. Ben shows her pictures of what her life once was. He tells her that she was involved in an accident ten years ago. This, he explains, has left her brain damage. This affects her memory in which she constantly wakes up not knowing anything of the day. Ben tells her that she's been like this since the accident. Ben leaves the house for work. While Christine looks around the house, a neurologist named Dr. Nasch calls the house. He informs her that she has been in treatment with him for the past few years. He tells her to locate a video camera which is hidden inside her closet. He tells her to watch the videos and to call him back. Christine watches a video diary of herself, which she is unfamiliar with. Dr. Nasch tells Christine to not inform Ben of the camera. Dr. Nasch also tells her that she lost her memory after she was attacked and left for dead at a nearby airport hotel. Christine wonders why Ben lied to her about the accident. Dr. Nasch tells her that it may be Ben's way of accepting her current condition.