In new British thriller Before I Go to Sleep, Nicole Kidman plays an amnesiac who wakes up each day with no memory of the past 20 years, due to a traumatic incident that left her physically and psychologically damaged. Gradually uncovering the mystery of her past, she must learn who to trust – her doctor played by Mark Strong, or her husband played by Colin Firth. Let’s call it Mumento. 

I’m going to try to write this review without making any obvious jokes about the sadly appropriate title, which won’t be easy given the disappointing drabness of the direction. It’s a great story, albeit a derivative one, and S.J. Watson’s source novel provides some strong ideas and characters to explore. But writer and director Rowan Joffe fails to capitalise on this potential, treating the material more BBC than B movie.

In the hands of Alfred Hitchcock, Christopher Nolan and Steven Soderbergh, this kind of mystery has enjoyed real success, because these are directors who aren’t afraid to have fun with the material and play around with the format. Let’s face it, it’s the same plot device as this year’s Edge of Tomorrow, so it’s hardly hard-hitting realism. But as the plot becomes increasingly ludicrous, Joffe’s misplaced sincerity only seems to grow.

Joffe offers scene after scene of people speaking softly in cars, spoon-feeding the audience information in a cheap attempt to create suspense. Every day, the doctor tells her some revelation about her husband, punctuated by over-the-top music, so she goes to confront her husband who then defends himself – and repeat, day by day. Why doesn’t her husband realise that she’s going to this doctor every day? What does he think she does all day? And how is she so adept at using a digital camera if she has no memories post-1990?

Kidman is otherwise convincing though, while Strong is impressive as always and there’s a welcome appearance from Anne-Marie Duff. Firth is brilliantly cast as the husband, but this is the biggest missed opportunity since, well, probably his last movie, Devil’s Knot. There’s so much potential, but executed in a way that feels oppressively respectable, conventional and safe. It does pick up towards the end, but not before you’ve gone to sleep. Oops, I didn’t make it.