Before I Go To Sleep poster debuts online

We've got our hands exclusively on the first poster for psychological thriller Before I Go To Sleep .

And it's as moody as you'd expect from the best-selling novel.

The plot finds Nicole Kidman as a woman who wakes up every day remembering nothing - the result of a traumatic accident in her past - until one day, new terrifying truths emerge that force her to question everyone around her.

Things get messy - and starry, as you can see from our poster below, which boasts Nicole Kidman, Colin Firth and Mark Strong in fine starey form.

Before I Go To Sleep hits UK cinemas 5 September 2014.