GIVEN that he'll turn 40 in May next year, overnight success can't come soon enough for Timothy Olyphant.

He's been grafting for years in television and on film, popping up in countless projects you'll probably have seen - Sex and the City, Scream 2 - but won't remember him from.

Thankfully, this makes him a most unaffected and entertaining interview. I have the pleasure of sitting down with him in London's Claridge's to discuss the project which may, fingers crossed, finally turn him into more of a household name.

Hitman, based on the Eidos computer game of the same name, is the story of Agent 47, a bald, tattooed killing machine who has been working as an assassin since being indoctrinated as a child. When his latest kill suddenly reappears looking suspiciously unharmed, it's clear that 47 has been set up - and must subsequently flee from both the FSB (the Russian secret police) and from the Interpol detective who has been on his tail for years.

Timothy is looking sharp in a suit today, and the first thing I notice is that his hair has grown back. Obviously, a bald bonce was crucial for the part, but I can't help but wonder if it was something of a crisis issue when he was deliberating over the part?

"I'll be honest. I thought the costumes were cool but the haircut - not so much. The day they shaved my head, my first thought was, "if only I could do this job with my hair". But you let that go after a while because there's something about the shaved head and the tattoo on the back of the skull that is really striking.

"There is something very violent and cold-blooded about 47 but, at the core, he's a guy who's doing his job, day in and day out. It seems like a rather lonely existence and he's emotionally detached from his work - I guess you'd have to be detached to do that job. But it's true of anyone in a very high-level position who operates on their own.

"(Such changes) are in the nature of these things - you know what you're signing up for."

And of course, the role was too good to pass up, given that it might secure him a future in bigger and bigger films?

He replies: "It was an opportunity to be the lead in an action film from a major studio, and that hadn't happened before so that was quite flattering. When I met with Xavier (Gens, the director), it was as if he wanted to make a character-driven film. I thought, "if I can get away with half of what he wants to, we might have something". He was also speaking in a French accent, which makes everything sound cooler.

"Xavier is a real cinephile. Sitting down and talking to him about his ideas and what kind of movie he thought this could be was the closer for me. He got me very excited about the project.

"If it wasn't based on a video game, if it was just about some bald guy, I wouldn't have!"

Of course, as much fun as there is to be had making a film of this nature, there may also be some limitations. Fans of the genre and - most importantly - the game itself will have expectations about the film's look. You don't want to get too ahead of yourself, or too carried away with your own ideas, I'd assume?

Timothy responds: "The action is why I go to see them. You want to see things go boom. Did I want to say, "My name is 47?" No. If I'd had my way he wouldn't have said anything. But no one's putting a gun to my head. I enjoy being part of these things."

Apart from the hair, the film required another physical transformation from the 6ft foot father-of-three, namely that he become as strong and fit as the role of 47 demanded.

Before commencing shooting, Timothy spent six weeks in a gym with a personal trainer, a man whose attitude he describes as "Let's bring Tim into the gym for an hour and a half and see if we can't make him throw up".

He elaborates: "It was physically demanding the day after. Those first couple of days I was sore - and I work out. There's a difference between going to the gym and going to the gym. It was maybe an hour and 15 minutes a day and it was so painful. Four or five weeks later, I was 15lb heavier, and it was all muscle. But it's nice to be paid for that.

"If you see a guy jump out of a window into a river, that isn't me laughs. But I did do most of the stunts."

Most recently, audiences will have seen Timothy in the role of Die Hard 4.0's baddie, Thomas Gabriel, a part which actually put his name in the frame for Hitman. The role wasn't such a physical one, but he did have the opportunity to watch legendary action man Mr Bruce Willis up close and personal, as well as spar with him in the film's final dust-up.

Did he ask his famous co-star for any advice about action roles or the business in general?

"You watch and learn. I don't remember asking him specific advice. But he couldn't have been nicer to me. He was very generous and he didn't have to be. We met on the set and he said, "So what are you going to do?" And I said, "Here's what I think".

"There was not really a clear character on the page. He was my biggest supporter and he encouraged me, backed me up. If there was an idea I had he liked, he was right there saying, "Let him do it".

"Also, it was so fun. That whole last scene (where Bruce kills him), I think we made it up right there on the spot!"