YOU know that Nash Edgerton was an active kid, riding BMX bikes and jumping out of trees with his younger brother around Dural, in north-western Sydney, from his broken noses.

The first was from a T-bar at the snow, the second from a cricket ball while fielding in slips, the next from a chlorine bucket lid being used as a frisbee and the fourth from a stray knee during a high dive.

That younger brother, Joel, grew up to star in The Secret Life Of Us, Ned Kelly and King Arthur while Nash has quietly built a career as a stuntman and short filmmaker with nothing like the same celebrity.

He was Ewan McGregor's stunt double on two Star Wars movies, was pummelled by Trinity in The Matrix movies and has appeared in Mission: Impossible II, Moulin Rouge, Superman Returns, Kenny, The Quiet American, The Thin Red Line and more than 20 other films. On TV, he has crashed a car for the Chaser team, abseiled in Police Rescue and, for a commercial, chased a runaway piano down a street.

You could say Edgerton is not a guy who walks away from a fight. Or a car crash. Or a jump off a very tall building.

His steadily rising career as a director has now taken him into a situation that must feel exactly like all of those things - with his first feature, The Square, being pitched into competition at the Sydney Film Festival.

Sure, you want people to see your film but do you really need 2000 people at the State Theatre comparing it to the latest from Mike Leigh or the hottest picks from Cannes? Do you really want years of effort, starting with a script that Joel worked on while filming King Arthur, to face a thumbs-up-or-thumbs-down verdict on one night?

At his Darlinghurst office -surrounded by piles of DVDs, trophies for various festivals and even a Jaws PlayStation game - Edgerton, 35, admits that prospect is "totally terrifying". But before he worries too much, there is the small matter of finishing The Square, a thriller about a construction supervisor, played by David Roberts (Ghost Rider, Fool's Gold), whose life unravels when he gets involved with a mistress, played by Claire van der Boom from Love My Way.

"It's a weird kind of pressure now," Edgerton says. "A lot of it is out of my hands because I'm not a sound designer and I'm not a film recordist and I'm not a composer. I oversee all that stuff but it's not like I can stay up all night writing the music."

In fact, Edgerton looks like he has been staying up all night. A very fit non-drinking, non-smoking, non-coffee imbiber, he has still been working long hours.

"That's OK," he says. "I'm fully like Last Minute Homework Guy."

Edgerton is likeably poor at self-promotion. Asked what audiences can expect from The Square, he seems unable to come up with, well, anything. Joel, who also acts in the film, is much more forthcoming, calling it "a story that packs a bit of punch about a person whose life becomes a slow train wreck after a couple of wrong decisions".

And Nash admits to being tested on many levels while shooting the film.

"I wasn't prepared for how much of a marathon it was," he says. "I've never been asked so many questions in my life by so many people, like the whole time.

"I snuck out to the tea and coffee area one night to have a break for a second and the unit guy is like, 'I got him.' I feel like I was just constantly being questioned."

Then there was the self-doubt.

"There were days when I feel like I had really good ideas. And there were days when I'd turn up and I had no idea what I was doing and I'd just make it up. Sometimes some of the best stuff came from that. You think, 'People know I don't know what I'm doing.'

"When I'd get home late at night, I'd have to shot-list for the next day but all I could think about was [everything] I'd f---ed up. It's such an up-and-down process."

Working on her first feature, van der Boom says Edgerton thought in images on set. "He knows what he wants to see and it's just a matter of getting into that mad brain and going with him for the ride." She describes him as "that dark cat who sits in the corner that wears the hoodie all the time but he knows who everyone is and he knows what's going on".

Edgerton, who lives down the road from his office with Joel, is part of a Sydney tribe of film obsessives who are endlessly enthusiastic about watching, discussing and making them. Another tribe member, who preferred not to be named, describes him as "a dark horse, one of the too-cool-for-school kids" with some well-known actresses as girlfriends over the years.

"My knowledge of any subject will eventually come to referencing a film," Edgerton says, still amused that he met someone who worked in real estate recently and all he wanted to know was what they thought of Glengarry Glen Ross.

The career in stunts came about in unlikely fashion. After finishing at Hills Grammar, which has also produced singer Delta Goodrem and The Chaser's Andrew Hanson, Edgerton was studying electrical engineering at university when he decided - just like that - to change directions.

"I looked up stunts in the phone book and found one number and I called that," he says. "I was determined that that was what I was going to be. I didn't know anyone in the film industry. I just kept calling them until I got to meet some people. I got to go out on a film set and met some more people. I'd go training with them."

Edgerton bought a car and practised stunts late at night and on weekends.

The brothers had already been making shorts with the family video camera.

When Joel entered Tropfest in 1997, Nash thought he should too and came up with Deadline, which had him racing through the city performing stunts to reach the festival office before entries closed. It won.

In 2005, he entered a second time with Lucky, which had him clambering out of the boot of a speeding car and fighting his way into the driver's seat. It came second.

His latest short, Spider, had him creating carnage by surprising his girlfriend with a plastic spider while she was driving. It won awards at Sundance, Aspen, Los Angeles, St Kilda and last year's Sydney Film Festival. These shorts - often based around stunts but still strong on story - were shot with whatever budget could be scrabbled together with close friends who work on each other's films.

"Usually I have an idea that just keeps recurring in my head," Edgerton says. "Spider and Lucky were ideas I had for a while. I'd constantly think about them or dream about them. Eventually I had to make them, otherwise it's going to drive me crazy."

Edgerton has also shot music videos for an indie collection of artists including Ben Lee - who has collaborated on the music for The Square, Eskimo Joe, Missy Higgins, the Sleepy Jackson and Toni Collette.

When it came to making a feature, he has one advantage of over many first-timers, having been on set with such illustrious filmmakers as George Lucas, the Wachowski brothers, Baz Luhrmann and Phil Noyce.

"Being a stuntman on those sorts of films has definitely been my film school," he says. "I didn't study film anywhere. I got to be on set and watch other people do it. You get to see it all happen and see what the end result is - see things that worked and see things that didn't work. I love doing stunts and being in other people's films and that's one of the reasons - to learn off other people."

There are similarities between stunts and directing, Edgerton says.

"At the core, stunts are about problem solving - how to do something that looks spectacular and dangerous but is achievable and repeatable."

But aren't stunts dangerous?

"You don't really think of it as that dangerous when you do it. You don't want to think that way. The fear factor usually comes out of messing up in front of the crew as opposed to getting hurt."

Edgerton has not even been thinking about winning the competition, though you get the impression the $60,000 prize money would go straight into another film and adding to the stack of DVDs.

"I just love working on films," he says. "I'd happily do a stunt job when I finish this or go and write something else or make something else. I guess I want to make more stuff while I still have the bug."

The Square screens at the State Theatre as part of the Sydney Film Festival on June 15 and 16. See www.sydneyfilmfestival.org