Before I Go to Sleep (2014)

Since it's listed as a horror and it has a very interesting cast --Nicole Kidman, Colin Firth, and Mark Strong--, I picked Before I Go to Sleep as one of the movies to watch this October (I'm doing 31 days of horror).

The film follows Christine Lucas (Nicole Kidman), a forty-year-old housewife who wakes up every day with a stranger in her bed, her husband Ben (Colin Firth), who explains to her that she had a car accident ten years earlier which resulted in a brain damage that erases her memory when she goes to sleep. One day, when Ben leaves for work, she receives a phone call from Dr. Mike Nasch (Mark Strong), a neurologist who is apparently treating her, who reminds her to record her thoughts and daily progress on a camera and instructs her to not tell her husband. Soon, she starts discovering the truth.