Death in a cold climate

Noel Clarke recovered from frostbite. J J Feild quit smoking because of hypothermia. Michael Fassbender survived shirtless sprinting in sub-zero temperatures to become the next Daniel Craig. It's true: whatever doesn't kill you makes you stronger. It just doesn't always feel like that.

On set in the highlands of Scotland, in March 2009, when it's not snowing it's hailing and when it's not hailing it's raining. And in those rare moments when fluid isn't flowing, the wind slaps the skin like an angry dad.

Neil Marshall, the writer/director responsible for carting cast and crew out into the wilds in winter is well-prepared, with a thick coat and ski goggles and a sense of humour shared by his associates. "Let's hope they survive to do the battle scene," says one wag, after watching the actors undertake the latest in a series of stunts. This one involved Fassbender, David Morrissey, Dimitri Leonidas and Liam Cunningham drifting free in an icy river, before hauling themselves ashore. Amidst the voluminous health and safety notes handed out to the crew, one sentence sums it up succinctly: "Actors are subject to risk of coldwater shock, hypothermia, water inhalation and drowning". The glamour of the movies.

For the sake of continuity with a previously shot scene, snow is being washed off surrounding stones when Cunningham and Fassbender wade in. It's horribly cold even in a thermal overcoat. In thin Roman-style tunics, it is literally freezing. Cunningham dips his head underwater and an expletive-laden shout echoes round the gorge. It's going to be a long day. And these actors have already been through extremes. "The first day was one of the most horrendous I've ever had," says Morrissey, sheltering from the elements inside one of the crew cars. "We were right at the top of a mountain, it was snowing, it was cold, we were running down 4ft of virgin snow. It was really full-on. But," he laughs, as it is now only a memory, "it was great to do."

Morrissey and Co form a pack of Roman soldiers fleeing a posse of vengeful Pict warriors, lead by the mute – but violently expressive – Etain, played by the Quantum Of Solace beauty Olga Kurylenko. Centurion is an action ensemble, bankrolled by the appeal of the former Bond girl, Inglourious Basterds star Fassbender and The Wire's Dominic West, who plays the hard-drinking, rabble-rousing commander of the Ninth Legion, the legendary outfit which mysteriously disappeared in Britain circa AD117. The film offers an explanation for their vanishing act (an event that's also pivotal to Oscar-winner Kevin Macdonald's The Eagle of the Ninth, out later in the year), but at heart it's a chase movie, with its roots in John Ford's iconic Western Stagecoach and John Boorman's survival classic Deliverance. That film was notorious for its gruelling shoot. Burt Reynolds' commitment stretched to being thrown down a vicious white-water drop – injuring himself in the process – only to be told by his director he looked, "like a dummy going over a waterfall". Marshall isn't so cruel, but he's definitely not kind: he wants what he wants.

"I think people get used to the way I work," he says. "I work fast. You don't get many takes – people have to kind of keep up with me, rather than me keep pace with them. I'm not very good at keeping them [actors] in cotton wool. I'm more: 'This is what we need to do, let's get on with it!' Everybody is there to do a job, you know? Especially on a film like this, there's no time for any of that. We've got to move. Everybody is freezing, everybody is wet, everybody is suffering. You've got to go!" The technique might not please everyone – there are a couple of off-the-record grumbles – but the lead has no problem with it. "Neil is one of those directors who really enjoys what he's doing," says Fassbender, over a cigarette in a damp tent erected for the actors to huddle in. "There's no fuss: it's bang, bang, bang. He moves at a pace and he's happy to be on set every day. He loves shooting entertaining films." "As with Neil, you have somebody who has written the script, has been there from the birth of the project, and he just lives, breathes and eats his work. So you just sort of go on set and try and learn as much as you can." Next, he's learning from Steven Soderbergh in the action-thriller Knockout, then David Cronenberg in A Dangerous Method, where he'll play the seminal psychologist Carl Jung.

Marshall couldn't be more effusive about the star (who – should you ever corner him in a bar – appears to know every single word of the screenplay of the 1985 Chevy Chase comedy Fletch and does an unbelievably good Christopher Walken impression): "He is absolutely dedicated." The 33-year-old actor even had to be talked down from undertaking one of the boldest stunts in the movie: jumping from the high-sided gorge into the inky, deep, rushing water. "He's up for anything, you know?" says Marshall. "Whether it's jumping into an icy, cold river or getting on a horse and riding at high speed. I'm sure if I'd said yes he would have jumped off the cliff into the river, but somebody had to hold him back and say, 'No, no, no, let's not get carried away here!'" (The stunt was eventually carried out by professional stuntmen, with suited-up safety divers lurking in the depths nearby.)

Perhaps the only person Marshall enjoyed working with more was his wife, Axelle Carolyn, who plays one of Kurylenko's warriors – though she doesn't have an easier time of it on set. Trussed up in battle gear, wearing war-paint and wielding a bow and arrow, she's made to wait to rampage as much as any other actor. A former journalist and author of the book It Lives Again! Horror Movies In The New Millennium, the 31-year-old is relatively new to acting and is justifiably wary of people's perceptions of a film-maker casting his partner. "Being known as 'the wife'!" she says, on the production's charter plane from Inverness to London. "Yes, it's a double-edged sword. On the one hand I know I have great opportunities because of who he is, but I don't want to just be the director's wife... And he did make me audition!"

Throwing herself into the gruesome action, she is certainly convincing on screen. "Oh, she justifies her place in the movie by delivering a great performance!" says Marshall, when asked in the editing suite about any cynicism surrounding her casting. "And, you know, I'm not the first director to put his wife in a movie!"