Christine Lucas (Nicole Kidman) wakes up with no idea of where she is – or who the man in bed with her is. Fortunately, the man (Colin Firth) knows what to do: his name is Mike, he’s her husband, and she has a special kind of amnesia that means every night when she goes to sleep she forgets everything she learnt during the day. In her head she’s still in her early twenties; in the mirror, she’s clearly pushing forty. It turns out she’s also undergoing treatment from a Dr. Nasch (Mark Strong), who’s given her a camera and asked her to record a video diary of her day-to-day life to help build up her memory. He’s also asked her to keep it hidden from her husband – but does he have a more sinister motive? Or is it Mike that’s keeping things from her? And if there are secrets in her past, are they hiding them from her because they’d be too much for her to handle – what, with only having a day to come to terms with them – or is there something hidden in her past that holds the key to her future?
This mystery-heavy story is hard to pull off, so it’s no real surprise that things start to get a bit wobbly towards the end. But the numerous twists and turns before that pile on the tension nicely, as the men around Christine manage to keep their various schemes and deceptions plausible even as the sense of menace grows.
Kidman’s performance goes a long way towards holding it all together, as she makes Christine convincing both as a damaged and fragile woman and someone determined to uncover the truth despite the formidable odds against her.
A tightly wound and claustrophobic thriller, this proves a little can go a very long way when it comes to building suspense.