Josh Hartnett: Tall, handsome and dark

Josh Hartnett tells James Mottram he wants to be seen not as a sex symbol but as a film-maker exploring life's sinister side

When Josh Hartnett walks into the room, you expect him to make an entrance like Trip Fontaine, the high-school heart-throb he played in Sofia Coppola's The Virgin Suicides. Then, he sauntered across the screen in swoon-inducing slow motion. Today, present at the Sundance Festival to promote his latest film, Lucky Number Slevin, he arrives in the basement of a Park City bar with less of a swagger to his 6ft 3in frame.

Wearing sombre navy jumper and dark slacks, this is the more real Hartnett; he's not the square-jawed military man of Pearl Harbor and Black Hawk Down nor the horror himbo from Halloween: H20 and The Faculty. Softly spoken and unfailingly polite, he has a bowl of brown hair, goatee and small green eyes that lend him the impression of being a "120-year-old Chinese man", as one observer recently put it. But then Hartnett has always seemed wiser than his years. While he jokes about his age by saying "27 is the new 17", it's evident he has no wish to turn back the clock to the days when he was dubbed "Hotnett".

Like most actors, he's forever fighting misconceptions about him in the press. He points out three. First, that he is an A-list blockbuster fiend. "I've always tried to do experimental work," he counters. "I've always tried to take the most interesting path. I think I've only been in a couple of big, blockbuster movies that were set out to be that way." Obviously, his idea of experimental - playing the Iago character in O, a wretched high-school version of Othello, or taking the lead in Wicker Park, a remake of the French thriller L'Appartement - would hardly cut it down the ICA, but it's the thought that counts.

Second, that he just wants to be an actor. "Ask any director," he says. "I've always wanted to be behind the scenes rather than in front of the camera." He is an executive producer on Lucky Number Slevin, though he received no on-screen credit for it. "I could call them up and put it in if I wanted to, but it's not really the point. For me, the point is learning the process in all regards, and when I decide to step out and do something else, I'll do it." After starting a production company named Roulette Entertainment with his actor-friend Eldon Henson, Hartnett sold a script to DreamWorks that never got made but was "pretty well received". He is now working on a second effort.

Minneapolis-raised Hartnett objects to his character being stereotyped. "Somebody wrote at some point that I was from the Midwest and that summed me up," he sighs. "If you asked anybody who knows me, I'm definitely not like most people there." It's this third misconception that grates on him the most. While he loved football, until a knee injury at 16 cut his playing days short, he grew up wanting to be a painter. "I had this sense that I didn't belong," he says. He describes his parents as "hippie-ish"; his father was a guitar player for Al Green before taking over the family real estate business, and his mother is a classroom assistant. They divorced when Hartnett was young, with his mother returning to his birthplace of San Francisco, leaving him and his three younger siblings to be raised by his father and stepmother.

He was taught to value happiness above material wealth. That's not to say he has not been swayed by the lure of the big payday - notably alongside Ben Affleck and Kate Beckinsale in the critically reviled Pearl Harbor. "That was one that was really difficult for me to make the choice to do, but everybody that was working with me said: 'If you don't do this, you'll regret it, because it will give you the opportunity to do all the things you want to do.' " Both the buddy-cop vehicle Hollywood Homicide and the limp sex farce 40 Days and 40 Nights were designed to propagate the Hartnett brand. "I went and I did a couple of movies that were in line with what people would expect me to do, but I didn't like it," he says. "You have to step back and say no."

Hartnett's latest film sees him partway through a process of reinvention, begun with a brief appearance in last year's Sin City. "I think I've always pushed toward the darker side," he says. "Every film that I've been able to break out of the box and play those parts - like O or The Virgin Suicides, which has a touch of darkness - I've always tried to make it psychologically based." Both Lucky Number Slevin and the forthcoming Brian De Palma adaptation of James Ellroy's The Black Dahlia cast him squarely in the murky world of the hard-boiled film noir.

"I saw a thing about Josh - he can be quite dark and he does it really well," says Lucky Number Slevin's Paul McGuigan, who previously directed the actor in Wicker Park. Hartnett plays Slevin, who - after a case of mistaken identity - finds himself caught between two rival kingpins, known as The Rabbi (Ben Kingsley) and The Boss (Morgan Freeman). He spends much of the film in just a towel, after he is abducted from the apartment where he is staying. He shrugs when I mention that acting with just a towel preserving his modesty won't harm his status as a sex symbol. "When people say that, it undercuts any ability you have, so I try not to focus on that."

At the end of the year, his transformation into a washed-up anti-hero will be complete, when he takes the lead in The Black Dahlia. It weaves a fictional story around the grisly (and unsolved) 1947 murder of the wannabe actress Elizabeth Short. Hartnett plays a boxer-turned-cop, Bucky Bleichert, who is working on the Short case when he becomes embroiled with a gangster's moll (Scarlett Johansson) and a bisexual society gal (Hilary Swank). A sexy cast, coupled with the reputed return to form of Brian De Palma, makes it an attractive prospect.

It also got him his first major celebrity girlfriend, in the shape of Johansson. She reputedly moved into Hartnett's Manhattan apartment over Christmas before accompanying him to the Sundance after-premiere party for Lucky Number Slevin.

Not one for the business end of things, Hartnett admits he has no love for Los Angeles, where an agent first took him for a whirlwind 50 auditions in under three weeks in 1997, after spotting him on stage in Minneapolis. Working in a video store in the evenings had turned him onto film, and he had vowed to head to Hollywood. When he did, he was initially turned down for the likes of The Thin Red Line and The Talented Mr Ripley before being given a reprieve of sorts as Jamie Lee Curtis's son in Halloween: H20. By 2002, he had moved back to Minneapolis.

He recently completed Mozart and the Whale, a love story with Radha Mitchell about a couple with Asperger's syndrome, which he says is "not about an ailment or a message". It's yet another attempt to secure a safe passage towards longevity in the business. "I think a couple of years ago I kind of made a decision to just do what I think is going to be interesting, something I'd like to watch," he says. "You spend a lot of time in this business worrying about what your next job is going to be or how people are going to respond to you. But I've kind of learnt not to worry about that now."

'Lucky Number Slevin' opens on 24 February