Matthew Fox had just been filming a night scene for Lost, and less than nine hours later had whizzed himself from location in the north shore of the island of Oahu to a meeting room in the building hosting the Grand Prix in Long Beach - all for a day or two talking up his latest film, Speed Racer, before flying back to Hawaii to continue shooting the rest of this season's episodes. This has been Fox's life for the past two years, a time he says he has worked 'non-stop', shuttling between the set of the acclaimed yet perpetually mystifying Lost, and his burgeoning film career. 'I'm going to take the summer off,' he announces resolutely, saying he will hop between Wyoming (his home state), Oregon and Hawaii for various leisure pursuits. 'I have no time to myself right now. I made the decision a little while ago to not work over the summer and I'm excited about that. Most of that time will be spent with my family, my brothers and their kids, my mother, and some close friends. It's going to be about spending time with the people most important to me.' At 188cm, with classically masculine features and a strong-silent persona, Fox is every inch the emerging movie star. Apart from his key role as doctor Jack Shephard on Lost, he also starred in Vantage Point earlier this year, a fast-paced action drama about an attempted presidential assassination, and which co-starred Dennis Quaid and Forest Whitaker. Before that, he was in the true-life sports drama We Are Marshall with Matthew McConaughey. In Speed Racer, perhaps his biggest movie to date, Fox plays the enigmatic Racer X. He is often sought out for big-name projects because Fox is on the periphery of that small clique of leading men who can open a movie - and he concedes that Lost had a lot to do with that. 'Lost has created these opportunities,' he says, extinguishing speculation that he might abandon the TV show for a more consistent movie career. 'I am committed to the show, I really enjoy playing that character within that world, and I'm very curious to find out where it's going to go. But I'm also really excited about the opportunities I'm getting to do outside because they are rewarding and rejuvenating.' Fox recalls a point when he had signed on for both We Are Marshall and Vantage Point, and lay in bed wondering if he had 'bitten off more than I could chew'. 'I worked six days a week that whole summer,' he says. 'But then I came back to Lost and while I was physically tired, I was rejuvenated by having the chance to go off and do these other projects, to look at the world through a different character. It was a good thing for me.' The producers at Lost, he says, are very accommodating, working with the studios he signs on with to free him up for what is already a gruelling shooting schedule; after all, good visibility for one of their leading stars in a top-rated movie is good visibility for him on Lost. 'They've been really co-operative and I'm very appreciative of that,' he says. 'There were some overlaps between Speed Racer and Lost, and so we ended up shooting a bit out of order for the TV show to accommodate me coming back from Berlin [where Speed Racer was filmed] three weeks late.' Signing on for the Wachowski blockbuster was a bit of a no-brainer for Fox, who immediately connected with the vision that the directors had for the special effects-laden film. Although he had never watched Speed Racer as a child growing up on his family's ranch in Wyoming, he went out and procured as many videos as he could once he signed on to the project. 'Anything you're doing - something that's based on original material - you want to spend some time with the source,' he says. 'I wanted to get the feel of who Racer X was in the context of the original cartoon. But ultimately it's about the new Racer X they had written, and what that world is.' Fox has two children (daughter Kyle is 11, son Byron is six), both from his 17-year marriage to wife Margherita Ronchi. He says part of the reason he signed on was he knew his kids would love the film, and that this would be the first thing he's done that was actually child-appropriate. 'I can't wait to sit down in the theatre and watch them watch the movie,' he says. 'I'm looking forward to that more than anything.' Fox started his career with his lead role as a brother who has to look after four younger siblings when their parents are killed, in Party of Five, airing from 1994 to 2000. He had roles in TV shows and movies once Party of Five ended, but probably didn't realise what a global phenomenon Lost would become when he first staggered into the camera frame in 2004. And there was no getting away from Lost. On the Speed Racer set, everyone wanted to talk to him about what was next up in the tangled lives of the island dwellers. There were lots of questions thrown his way, but Fox says by now he knows how to handle it. 'It always happens,' he says. 'But it's kind of like with a wink.'