Annie's relationship with her brother is the emotional heart of the film. Tunney explains how the siblings withdrew from each other in the complicated aftermath of their father's passing: "In the three years since their father's death, Peter's thrown himself into photography and has been incredibly isolated. My character has thrown herself into climbing, the sport that her father loved and she also loves. That's her way of grieving."
Tunney was also fascinated by the questions Annie must face once she is trapped in the ice cave with Elliot Vaughn, whose philosophy on surviving the catastrophe is diametrically opposed to hers. "She'd rather give her life to save somebody else's, and he is more 'survival of the fittest,' out for himself," says Tunney. "I don't think that's right or wrong. I think everybody can say ideally how they would react in a life or death situation. But we don't really know unless we've been in that circumstance, and I think that's one of the interesting things in the movie.
Like O'Donnell, director Martin Campbell was a major factor in Tunney's accepting the role of Annie. "He's amazing. He's incredibly good at the technical aspect of filmmaking, but he really pays attention to the actors, and he'll keep going until you get it right. He knows exactly the film he wants to make in his mind— every single second of it.
"There's also the fact that he put together such a good group of people. Everybody m the cast was so nice, and there was always somebody to make you smile. It was easy to be on set because nobody pulled any strange attitude about how uncomfortable they were or how important they are."
Like many of the other actors, Tunney relished the opportunity to learn to climb and quickly became adept on the mountain. "Even though we were only at 10,000 feet, and we are supposed to be at 26,000 feet in the movie, it was challenging. This was a very extreme way to make a movie.
Bill Paxton came aboard to portray wealthy, self-centered entrepreneur Elliot Vaughn, whom some might consider the villain in the movie. "He makes no bones about it— he's a self-made man," says Paxton. "He believes that when you're up on a mountain you have to take responsibility for yourself, and that self-preservation is the nobler pursuit.
"Does that make him a villain?" asks the actor. That is for audiences to judge.
Like Tunney, Paxton was fascinated by the moral questions the film poses. "In this movie, the mountain represents different things to different people. For my character, he's going to go up the mountain just to look at the view and look at his own domain. He pushes these people into a very dangerous situation through his own blind ambition. He has no qualms about leaving anybody up there.... we're all adults, and we've made the choice to be up there. Now, that's a cold point of view, but that's a realistic point of view."
Paxton also looked forward to learning the art and science of climbing, especially from Vertical Limit's expert consultants. "It's always fun to learn respect for a different profession," says Paxton. "Some of the stories that these guys have are amazing. They have been in truly life and death situations."