One of the best-received films at this year's TIFF, Atonement tells the story of a 13 year-old girl who, thinking she's doing something right, actually does something horribly wrong and starts a chain reaction of terrible events that will go on for several years. To say more than that seems unfair, since this is the kind of film that everyone should go into tabula rasa the first time, if at all possible. However, those who have read the highly-praised novel by Ian McEwan already know the ins and outs and can marvel at how delicately and faithfully McEwan's prose has been brought to vivid life on the screen. Christopher Hampton, the film's screenwriter who also penned Dangerous Liaisons, agreed to sit down with Cinematical at this year's festival and talk about the unique challenges of creating a film script that could capture everything great about McEwan's writing and working with Joe Wright, who is proving himself to be one of the most clever and talented filmmakers in the business today. Here's the interview.

Cinematical: Talk a little about the third part, the nursing section -- did you feel, as I did, that Briony paints herself a little too well in that part? When I doubleback after the ending, I look at that section suspiciously, like maybe she's taking liberties with the truth.

CH: The whole motivation of that nursing section -- which, by the way, I think is sort of the best written bit of the book, really exceptionally precise and well-pictured -- I think she throws herself into this job out of guilt. The book is about a life, her life, being ruined by the knowledge that she's ruined other people's lives. I see no reason to doubt her sincerity, although you're perfectly free to do so.

Cinematical: What were the major challenges of adapting the latter part of the book -- part three and the 1999 afterward?

CH: That was a particular problem that one had to find a solution, to find a way to crack it, and in fact what we wound up with was something that was the briefest of the many versions that we had done. You tend to elaborate, when you've got such a complicated thing to get over to an audience. Then we sort of thought, the shorter and more lucid and simpler we did it, the better it would work. But to answer your question about part three, in my original first draft, I had conflated the Dunkirk section and the hospital section. I had intercut, you know, gone back and forth between them. And at a certain point, I decided to go back to what the book does, which is keep them in sections. They are simultaneous in time, those two sections, so it was worth a try. But there's something about having the focus on each character, chapter by chapter, that works very well. Also, it works because Joe made the very smart decision ... there was a lot of talk about whether we could get one actress to do the child and the 18 year-old. You know, if we'd found someone, I could have upped the age to 15 or something, but of course it's not about a 15 year-old. So Joe was very clear about that, and that was a great help, that he said 'no, no, we're gonna have two different actresses.' So that also assisted the idea of focusing on one character at a time somehow.