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Exclusively released to The Independent, the pictures feature Kidman as 40-year-old Christine Lucas, who believes she is just 27 following a traumatic accident that leaves her clawing for the truth – until one day she is forced to confront new and terrifying truths.
The film, directed by Rowan Joffe, also stars fellow Academy Award-winner Colin Firth as Christine’s husband Ben, whom she no longer remembers.
And Mark Strong completes the starry cast as Dr Nasch, the man who may or may not be helping Christine to regain her memory.
Kidman, who undertook extensive research for her role, said: “I watched a number of documentaries where people do have this psychogenic amnesia. The idea of actually having this is horrifying.
“Someone described it as like losing their soul, because you lose your identity, you lose actually what you are and that’s really chilling, and it’s also sad.”
As Christine's carer, Ben is tasked with choosing whether to remind her each day that she is married to him and that they are parents to a son.
“It’s a massive task for him,” Firth said. "To decide to be the sole carer for somebody for whom every waking moment is a crisis… It’s immensely trying to him, to breaking point.”
Based on the novel by SJ Watson, Before I Go To Sleep questions the extent to which our memories make up our identity.
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The movie, much of which was shot on a handheld camera, has been adapted by Joffe after Ridley Scott acquired the film rights.
The director said: “What’s great about this story is that you are never sure whether you are watching a movie about a woman who, as a result of a brain injury, misconstrues the world around her and believes she is the victim of a conspiracy.
“Or a thriller in which a character with amnesia is being exploited for some nefarious ends by the men around her and she needs to figure out what, who and why quickly or she’ll be in jeopardy.”
The film will hit cinema screens on 5 September 2014.
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