The bowels of the Caledonian Hotel, that red sandstone flagship at the West End of Princes Street, are bubbling with activity. Perhaps ‘bowels’ is too scatological a term for the genteel, 104-year-old Edinburgh landmark. Consider instead how these behind-the-scenes corridors and service lifts pump the hotel’s lifeblood to its pampered surface. Today, however, those arteries are clogged by cameras, cables and acting extras as Hallam Foe – director David Mackenzie’s follow-up to Asylum and Young Adam – creates a movie location beneath the feet of unsuspecting tourists.

The film, which has its UK Premiere at this year’s Edinburgh International Film Festival (EIFF) was shot in the Scottish capital last year. Edinburgh is no stranger to Mackenzie’s work – Young Adam opened the 2003 EIFF and his first short, Dirty Diamonds, played here in 1992. Nor is Mackenzie a stranger to the Caledonian Hotel. Taking a break from gazing into the monitor that captures Jamie Bell and Sophia Myles in action, he remembers the first time he set foot on these plush carpets.

‘When I was 17, I got my first non-school job as a room-service waiter at the Caley,’ he says. ‘So this is quite weird. Walking around, I can’t tell who is an extra and who is the real thing. It means that the little things we’re doing have a vague authenticity to them.’ He takes in his surroundings, contrasting the smart front-of-house uniforms to the functional world where he has set up shop today. ‘Right from when I worked here, I’ve always been amazed by the difference between the chi-chi outside and the staff areas; you go through a door and there’s no attempt to paint it.’

You could almost say the same for the themes that recur in Mackenzie’s films. The outward exterior of a character is one thing; the unadorned, raw psychology beneath is where the 41-year-old director really focuses his attention. Think of Ewan McGregor’s sexually devious barge-worker in Young Adam, the adulterous Natasha Richardson in Asylum and in Hallam Foe, the peeping tom title character, played by Jamie Bell.

Hallam is one of the most messed-up, voyeuristic characters in recent literature. If he’s not spying on people from a tree-house on his architect father’s Borders estate, then he’s clambering over Edinburgh’s Old Town rooftops peeking in the skylights. His beloved mother drowned after taking an overdose of sleeping pills, although Hallam is convinced that his father’s new wife had a hand in this supposed suicide. Then again, he harbours strong sexual feelings towards his stepmum and, when they spill over into action, he flees the family home for Edinburgh.

After roughing it on the city streets, he accidentally spots a woman who is the spitting image of his dead mum. Kate is the human resources manager of a big hotel, and, after securing a job in its kitchens, Hallam strikes up a friendship with his boss while secretly watching her in her flat through a pair of binoculars. Although she is already having an affair with the married hotel manager, Kate and Hallam’s relationship also becomes physical. An evil stepmother, a mummy lookalike - it all becomes something of a . . .

‘. . . Freudian fairytale,’ says Mackenzie, ‘that’s a good way of putting it. An Oedipal adventure.’

Mackenzie has taken major liberties with the story as it appears in the novel by his old friend Peter Jinks. Most notably, Hallam’s Edinburgh employment has shifted from a charity organisation to the hot, clattering hotel kitchen where Jamie Bell finds himself this afternoon.

‘It’s all the down-and-dirty stuff that we’re doing today,’ explains 21-year-old Bell. ‘Hallam has just been employed as a kitchen porter, which is the lowest ranking position you can probably have in a hotel. We’re about to do a couple of montage sequences where Raymond – who’s played by Maurice Roëves – is showing him the ropes of what a kitchen porter would do every day.’

After a startling debut in Billy Elliot, aged 14, and a return to school, Bell seemed to struggle to find his form as an actor until a string of foreign independent features – Undertow, Dear Wendy and The Chumscrubber – helped his natural talent flourish, casting him each time as a tortured but sympathetic soul. Then the Hollywood big guns came calling. Back to back, Bell played the cabin boy in Peter Jackson’s King Kong and a young American soldier in Clint Eastwood’s Flags of Our Fathers. He worked with Jackson just after the New Zealander won the Best Director Oscar for The Return of the King and with Eastwood just after the veteran won the same award for Million Dollar Baby. Which of course means . . .

‘. . . David will win next year, yeah.’ Joking apart, Bell does compare Mackenzie very favourably with his illustrious predecessors. ‘I love that David keeps it local. Coming from the North East of England, where it’s all about local pride and staying close to your roots, I look up to people like Peter Jackson who use their culture and are proud of it. And you can see that burning desire within David as well. He uses Scottish people, he uses Scottish material, his crew, the accents, are all Scotland.’

Bell also reckons that Mackenzie’s approach is as precise as that of the former Dirty Harry. ‘The good thing about David is that he knows what he doesn’t like. You’ll try something and he’ll say, “No, not in that direction – that’s not where we’re going with it”. And that’s great because you start narrowing things down. Clint is actually quite laid-back. One or two takes, that’s about it. I think that comes from having been an actor for 50 years. He knows the game, he knows the tricks that you’re going to call, he knows that a director is going to use certain bits of little takes. He wants to take the drama out of everything because it’s just a job. But he’s Clint Eastwood, you know? And so you trust him and just get on with it.’

With Bell back in front of the camera, going through some additional hotel chores with Roëves and Trainspotting star Ewen Bremner, Sophia Myles – who plays the hotel HR manager with an uncanny resemblance to Hallam’s mother – has time to chat. She too is impressed with Mackenzie.

‘I met him before I’d even seen any of his stuff, and I liked him as a human being,’ she admits. ‘I just thought, “You’re a bit of a genius”. He’s really passionate about the project and he doesn’t have an ego.’ Now that she has seen Mackenzie’s earlier films, is she ready to explore the erotic tension that was so tangible in Young Adam and Asylum? ‘There is sex and there is nudity, but it’s not . . .’ She breaks off for a moment. ‘Well, for me personally, when I read the script, I don’t think it’s erotic. David really likes to get to the bottom of human interaction and human sexual desire. He doesn’t beat about the bush with it – he just gets straight in there.’

For his part, Mackenzie is the first to admit that the subject matter that intrigues him is a bit outside the cinematic mainstream. But there’s a younger drive and energy about Hallam Foe that could well break his work to a wider audience. The film features a title sequence animated by David Shrigley and an exceptionally cool soundtrack dominated by Scottish talent such as Franz Ferdinand, Sons and Daughters, King Creosote, James Yorkston, Future Pilot AKA and The Pastels. That’s not just a cynical marketing ploy; it’s a strong commitment to a creative scene up here by a director who, with four feature films in five years, is prolific by modern standards.

‘Well, not by Michael Winterbottom’s or Woody Allen’s standards,’ he counters. ‘But I find it more stressful not to be working. I get anxious when I’m not working. I started quite late, so I thought I had some catching up to do. All those years, hovering around the Edinburgh International Film Festival, looking sheepish and trying to make short films. But now, being allowed to make films properly . . .’
He breaks off into a smile, before being called back to his monitor for a chat with cinematographer Giles Nuttgens, who is setting up the next shot. For all the backstage buzz down in the hotel corridors, the mood on set is happy, with the actors clearly supportive of their director. Or maybe it’s just down to the fact that they have rarely had such little hassle getting from their accommodation onto a film set. ‘We’re living in this hotel now,’ says Myles, ‘which is great. You just roll out of bed and fall into the make-up chair.’

Hallam Foe, Cineworld, Fountainpark, Dundee Street, 0131 228 2688, 15 Aug, 9.30pm, prices start from £6.50 (£4.55).