I have an enormous amount of respect for Nicole Kidman. She's just done so many great movies and she's been out there at the forefront of carrying films and being a movie star. On set, it really pays dividends because when you're performing with her, she knows exactly how to play it. You don't have to compensate for her in any way.

[Before I Go To Sleep] script was a great journey with all the twists and turns that were kind of unexpected. I had to finish the script, and I thought if we can emulate this in the film, it's going to be a really good film.

In the movie, you have to decide as an actor how you are going to give a character presence. You can't really move, walk, and talk like yourself. This creates something so you have to find something "other".

If you think about Shakespeare, you remember Richard III and Macbeth before you remember Ferdinand, whose role is just to fall in love and be a bit of a wimp. I love the baddies. More important, though, is making the baddies somehow, weirdly, understood.

I got sent the script [ Before I Go To Sleep] as usually happens and you have a little look. I know it's a bit of a cliché, but it was absolutely a page turner. I mean, I wanted to find out what happened next.

The idea of transformation - playing something I'm not - is the bit I enjoy most about acting.

I had this extraordinarily bizarre moment when, two Fridays ago, my missus gave birth to our second child at 11am and by the same time the following day I was sitting around a table with Ridley Scott, Russell Crowe and Leonardo DiCaprio in Rabat in Morocco, rehearsing a scene we were going to shoot the next day.