He's the star of the acclaimed 24 and tonight he'll save America one more time as the latest series reaches its climax. But life hasn't always smiled on Kiefer Sutherland. After Brat Pack superstardom his career nosedived, then Julia Roberts ditched him. So he sought solace in rodeo riding and drink before fi nally fi nding redemption, he tells Stephanie Merritt

Tonight, maverick counterterrorism agent Jack Bauer will save the world (or at least the part of it that matters most, the greater Los Angeles area) from Armageddon for the fifth time. Not that I want to give away the ending, but the fact that Fox has commissioned a sixth season of 24 and optioned a seventh and eighth and a possible feature film is a clue that Bauer will probably escape the clutches of his multitude of enemies on both sides of the law and live to battle several ever more improbably Byzantine plots to derail the West.

Bauer is a hero for our time, arguably the greatest action hero of modern screen drama; notwithstanding the fact that he apparently never needs to eat or sleep, he is riddled with human flaws in a way that Bond or Jack Ryan never were, dramatised most explicitly in his fraught relationship with his teenage daughter, Kim, and his confrontational attitude to authority.

More boyish than his on-screen alter-ego, unobtrusively sipping pineapple juice in the corner of a quiet London hotel bar, Kiefer William Frederick Dempsey George Rufus Sutherland (yes, really) waves aside the suggestion that the ante has been upped so far that the storylines can only become more and more unfeasible.

'We didn't think it could be sustained after two years, so the writers have done a fantastic job,' he says, with understandable loyalty. At 39, he has spent 15 hours a day, six days a week, for the last five years on the set of 24, where he is also an executive producer. The show has not only earned him a Screen Actors' Guild award, a Golden Globe and an Emmy nomination for every season, but revived a stalled acting career and has made him one of the most recognisable faces on American television.

24 revolutionised television drama with its ambitious real-time format, but you can't help feeling that the timing, more than anything, though not anticipated, has been crucial to its success. The first series was broadcast in the US in November 2001; the notion of global terror plots to topple the US by slaughtering thousands of civilians was no longer a pleasantly thrilling B-movie fantasy but a reality. It made us all feel a bit better to think that there might be men like Bauer - flawed, yes, but committed and possessed of a strong moral compass - keeping tabs on the terrorists rather than the seemingly clueless troupe of improvisers actually in Washington.

Since then, 24 has capitalised on its timeliness by skirting ever closer to political reality, even while its plotlines veered towards melodrama. We have had Middle Eastern terror networks, Russian separatists, biological and nuclear weapon threats and Machiavellian conspiracies and cover-ups in the corridors of power. Has the show consciously become a forum for a political message? 'Well, take a look at where the President's been going with this one,' says Sutherland.

In season five, corrupt President Logan begins by engineering a war in the Middle East to secure oil revenues (imagine!) and ends up in bed with terrorists aiming nuclear missiles at California. Liberal fans are less delighted by the question of Bauer's cavalier attitude to the Geneva Conventions; his interrogations are closer to the MO of Guantanamo or extraordinary rendition than would seem proper for the good guy.

'There are aspects of 24 where I love its politics and aspects where I hate them,' says Sutherland, though he doesn't usually exercise his executive control over the storylines. 'My input is that if it's going in a direction I really don't like, then I will say something and we'll work together, but the writers and production staff are upstairs and we don't usually interact.'

He describes his politics as 'liberal, with common sense'; his mother, actress Shirley Douglas, was the daughter of Tommy Douglas, leader of Canada's New Democratic party, 'the first socialist to come to power in North America', as Sutherland proudly describes him.

His father is iconic actor Donald Sutherland, who separated from Douglas when Kiefer and his twin sister, Rachel, were four and Donald was having an affair with Jane Fonda. Their mother disappeared for six months, leaving the children in Los Angeles with their father, then returned and took them back to Canada, where Kiefer attended seven different schools in 10 years, ending up at Toronto's exclusive St Andrew's College, from which he dropped out at 15 to pursue acting. Was he never intimidated by his father's fame?

'I got really lucky in that my dad stopped working just as I started. He took a few years off, not on purpose, but he has three sons with his wife of 30 years and he wanted to be involved with them. As much as I missed him being around when I was growing up, I think he missed us too and he wasn't going to let that happen again. So it wasn't until much later that people started making comparisons. When I started, with films like The Bay Boy and Stand by Me, I look back on those interviews and I'm amazed; there's no mention of my father, it's not even "son of Donald Sutherland". I caught a bit of a break in that it never felt like a weight to me. It's amazing that I was stupid enough to try it - we're talking about one of the most prolific actors in film history - but my parents were very gracious about making me feel like I at least had a shot at making my own path.'

The Bay Boy was an early film role, at 16, which saw him nominated for Canada's equivalent of an Oscar; by 21, he was in Hollywood, having appeared in a Spielberg television series and starred in three seminal Brat Pack movies: Stand by Me, The Lost Boys and Young Guns. He had married actress Camelia Kath and had a daughter, Sarah Jude, now 18. Does he feel, looking back, that he had a pretty easy ride to his early success?

'If the acting thing hadn't worked out for me, I'd be laying phone cable in northern Ontario.'

That's not really true, though, is it? Donald Sutherland's son laying cable? He grins and shrugs.

'Well, that was a summer job I had. But I'd left school early. I had a year to get this acting thing going; it's not that it's been an easy life but fuck ... I've been lucky, yeah, and I am aware of that. I've had opportunities that 0.0002 per cent of the people in the world have, so do something with them, don't be an idiot.'

His first marriage lasted only a couple of years, reportedly because of his predilection for drink and women, and, in 1990, while making Flatliners, Sutherland fell in love with his co-star, Julia Roberts. Their engagement made them the tabloids' First Couple of Hollywood, the Brad and Angelina of their day, which made the headlines all the more gleeful when, just days before their wedding, Roberts called it off and ran away to Europe with Sutherland's then best friend and Lost Boys co-star, Jason Patric.

He recently said of the experience: 'I commend Julia for seeing how young and silly we were, even at the last minute, even as painful and difficult as it was. Thank God she saw it.'

Perhaps he can afford to be gracious after 15 years, but I am more surprised by his forgiving attitude towards the tabloids, which have paraded every blip in his private life since then, including his four-year second marriage to model Kelly Winn, and his tendency towards wild nights, bar fights and the odd arrest for driving under the influence.

'You can't ask the press to service you with everything that they have and not expect some of the other stuff in return if you're going to live your life like I have,' he says. 'I've done enough stupid things that I might as well walk up to them and say, "Here, if I were you, I'd write it like this ..." In all fairness, the press has been pretty nice to me; even in having a go at me, it's done with a kind of humour. Only once or twice have I seen something that made me think, wow, that person really doesn't like me - where it's been malicious as opposed to "what an idiot".'

After the humiliation of the Roberts debacle, Sutherland's career seemed to take its cue from his romantic life. He was taking on negligible and sometimes downright risible roles to pay the bills until he decided to take some time off from the profession altogether and left Hollywood for a Californian cattle ranch. Here, he took up professional steer roping and, although he broke three fingers at his first rodeo, he persevered until he became a tournament-winning rider on the rodeo circuit and was finally accepted by the other cowboys as more than just a dilettante.

'For the first year I was there,' he said, 'they made fun of me. I think that they ended up accepting me more for the fact that I took that for a year than that I turned around and could actually rope.'

Though he returned to Hollywood in 1996, it was not until 2000, when he received a call from British director Stephen Hopkins asking if he would be interested in the pilot for an experimental real-time television drama, that his luck finally returned.

In the course of talking about his father, he observes that the mark of the true artist is never being willing to compromise the purity of what you do or the choices you make. I ask if he has regrets about his own choices.

'No, I don't, but ... [he pauses and considers] you know that moment when you go, "Why is this happening?", you have to look back and realise you set it in motion ...' He stops again and takes a different tack. 'I've been keenly aware of the choices that I made. I got married at 19 and there are a lot of things I did in my career, some successful, some not so.' He sits forward, suddenly animated. 'You know, Gauguin is one of my favourite painters, not because I think he was a great painter but because he was a great artist, his passion and belief in what he was doing; he gave up everything to follow his passion. I have so much respect for that because I don't have that kind of courage.'

Sutherland's commitment to his work on 24 has meant that, like Bauer, he doesn't get time for any kind of meaningful or lasting relationship. Instead, he has turned to his other great passion, music, and set up an independent record label, Ironworks, with his producer friend, Jude Cole. The first group they have signed without partnership with a major label is fronted by a 28-year-old LA blues-rock guitarist and songwriter, Rocco Deluca, whose first album, I Trust You to Kill Me, was released here in the spring.

To promote it, Sutherland accompanied the band on a five-date tour of tiny European venues, a trip that was the subject of a recent documentary of the same name. Rather than an account of a young band's struggle to get ahead, the film turned out to be an intimate portrait of Sutherland's inner landscape.

'It was almost like saying goodbye to a time in my life,' he says. 'I've been alone for a long period now and everything was about work, and then, when I wasn't working, I would just go off and pop, you know.' He nods meaningfully; this is a euphemism for the nights of drinking that have kept the tabloids busy, including the recent incident, captured in the documentary, when he rugby-tackled a seven-foot Christmas tree in a London hotel during a post-gig party.

'I think there must have been a part of me that knew it was time to change my life. One of the nice things about the tour was that it was a kind of a ... not exactly a last hurrah, but I knew stuff was going to be different after I got back.'

For someone notoriously guarded in interviews, it seems curious that he would choose to allow such an intimate film, one that frequently shows him drunk and emotionally confessional, to be made. What were his motives?

'It made me very uncomfortable, but I could see that I was saying goodbye to a part of myself that had to change, so it ended up becoming a much heavier experience than I anticipated. I thought I was just going to go for a laugh.' He grins. 'I've never apologised for who I am. I've done some things that I've had to apologise to my family for, but we are who we are and people have been really cool with me; on some level, it's better coming from me than from someone else. I showed it to my daughter and she loved it, though I don't know how my parents will react.'

So Bauer will be around for a little while longer. The projected movie version of 24, if it happens, will be filmed after the sixth series, 'but that won't be in real time,' he adds reassuringly, and explains that season six will take a slightly different turn. 'We've had five years of him saving a large thing; this one's much more about him saving his own ass. He'll go from being the one who hunts people down to the one who's being hunted, so that in itself turns the show around.'

Meanwhile, Sutherland has been giving some thought to other avenues he'd like to pursue creatively. 'I have a very strong political outlook and that is something I'd like to take more responsibility for in my life. I don't believe in utilising certain aspects of the power I have with celebrity to push that forward, but I would like to make some films that address some of those political issues. The first film I ever directed [Last Light] dealt with the death penalty - I'm a staunch opponent - and it was a tiny, million-dollar film, but it was one of those great moments in my life that felt like you are taking advantage of an opportunity and doing something good with it; I did feel good about that.'

Does he think there's more of an audience now for politically charged movies?

'I think the audience has always been there; I just don't think the material was. I really salute someone like George Clooney - there's a perfect example of someone who's really making something work. You don't have to agree with his opinion, but I love the fact that he's decided to take his opinion and make films with it, as opposed to making meaningless films and then just talking the talk. He's doing it with his work and, if I was ever going to be political on some level, that would be my avenue to do it.'

Is this something he has plans for?

'Oh yes,' he says, deadpan, and then, self-mocking, adds: 'I just haven't quite worked out how to do it yet.'

Not to worry. Like Bauer, he seems to have a knack for getting around obstacles.

· Season five of 24 ends tonight on Sky One & Sky One HD at 9pm

Life story

1966 Born 21 December, in London, to parents Donald Sutherland and Shirley Douglas . His family moved to Los Angeles soon afterwards.

1970 Parents divorced. Kiefer and his mother later moved to Toronto. 1983 Returned to the US to launch his acting career in New York. His first major role came in 1984 in the Canadian rites-of-passage tale, The Bay Boy.

1987 Appeared in vampire movie, The Lost Boys, with other Brat Packers. 1987-90 Married to Camelia Kath with whom he has a daughter, Sarah Jude.

1991 Was engaged to Julia Roberts; the relationship ended days before their planned marriage.

1992 Appeared in A Few Good Men.

2001 Starred in the first series of 24 as Jack Bauer.

2006 Became the highest-paid actor for a drama series when he signed a $40m contract with Fox to play Jack Bauer for another three seasons.

24 things you didn't know about 24

1 Jack Bauer has killed 112 people over the five years of the show. Season 4, during which he dispatched 44 'hostiles', was his best ever; in the first season he managed a lacklustre 10.

2 Kiefer Sutherland heard that American college students use 24 as a drinking game, downing a shot every time Jack Bauer says 'damn it'. So he changed the script in one episode to have Jack say 'damn it' 14 times in one hour.

3 Another frat-house game is to monitor Jack's flouting of the Geneva Conventions. In season 2 he shot a key suspect under interrogation in the heart before beheading him. In season 3, he executed a colleague on the president's orders.

4 Jack's entry codes for CTU (Counter Terrorism Unit) are 4393 and Q22Q17

5 For season 2, a prototype script was written in which each (non real-time) episode would span 24 hours, but execs decided to stick to the original format.

6 During season 4 an incoming call number was shown on a character's mobile phone. More than 50,000 fans dialled the number - only to find it was real and belonged to one of the crew.

7 More than 20 lead characters have died in seasons 1-5.

8 Jack Bauer has actually died twice. In season 2 he was tortured, burned and tazered to death before miraculously coming round. In season 4 he was shot dead; then Tony Almeida injected him with epinephrine and he recovered.

9 Executive Producer Evan Katz once said: 'We make a lot of it up as we go along.'

10 24 was the first TV show to embrace real-time - the clock keeps ticking during ad breaks and there are no flashbacks.

11 Of course, it's not quite as simple as that. Three minutes are in fact gradually added to the timer during the ad breaks.

12 Almost all scenes are shot at head height.

13 We've never seen Jack eating, sleeping or going to the toilet. As a joke for season 5 he was filmed exiting the bathroom, eating a sandwich and wearing his pyjamas. It didn't make the final cut.

14 What might have been: 'The original iteration of 24 was that we were going to do 24 hours in the life of a wedding ... kind of a romantic comedy series.' (Creator Joel Surnow)

15 In the US, the Fox network had to screen adverts during season 4 episodes showing 'positive' images of Muslims, to counter charges of Islamophobia.

16 Everyone on the programme has to sign pledges not to reveal the plot.

17 Former presidential candidate and Republican Senator John McCain is such a fan of 24 he landed himself a walk-on part.

18 Blooper alert! The Californian presidential primary - the backdrop to season 1 - is held in March, not June.

19 The premiere was due to air in the US just one month after 9/11. Following the attacks, a shot of a 747 exploding was removed and the screening was delayed.

20 Jack's daughter, Kim, has been held captive in one form or other eight times.

21 Sarah Clarke was cast as Nina Myers on the morning filming was due to begin for the pilot episode.

22 Glenn Morshower, Kiefer Sutherland, Carlos Bernard and Dennis Haysbert are the only actors to appear in all five seasons.

23 To speak fluent Jack, use the following phrases often: 'Where's Kim?', 'Who are you working for?', 'Get down on the ground!' and, of course, 'Damn it!'

24 Fox commissioned two more series of 24 in May. A feature film will begin production next year, with parts to be shot in London.

Benji Wilson