On what attracted him to the project -- Matthieu Kassovitz: "The book was a best seller in France, and the producer came to me with the project. Jean was already interested in playing the lead, and I also thought it was a good chance to work with Vincent again. So getting this script was like a big present for me, also because it was suspenseful and contained a lot of very cinematic imagery. So it was interesting work for me."

Kassel, Reno and Kassovitz at a Tokyo press conference last month.

On the difficulties of the shoot -- Jean Reno: "We were shooting on a really high mountain, and the air was really thin, so it was difficult just trying to move. It was around -19 degrees in the morning, so it was hard just to open your mouth and have words come out. It was hard for the cast, but even harder for the director and crew I think. Of course the entire film is based on this premise of coldness, so I think filming in these horribly cold conditions worked in making the film more effective overall. That's what they pay me the money for, anyway. But it was, in fact, a really dangerous shoot."

On his fight scene -- Vincent Kassel: "I didn't train in particular for this scene, but originally, I trained in the circus as a dancer. But in the hand-to-hand fighting, the two guys I fight are people I've worked with for a decade. One is a Brazilian; he's a dancer who does the capoeira style. The other guy is a kick-boxer. I practiced the moves with them for over a month and a half. These sort of fight scenes are about kicking heads, but for me, they have the same quality as dance, the beauty of bodies in motion. Fred Astaire, Jackie Chan -- same thing."