At 30, Stephen Multari is not just an actor who's already amassed a sizeable list of stage and screen credits; he's also a producer. Not only does he play one of the lead roles in 4000 Miles, he was also a driving force in bringing the award-winning American play to the stage in Australia.

Multari says, "This is the third incarnation. It was initially the idea of MopHead Productions, the theatre company I run with Eloise Snape, who's playing Deirdre."

4000 Miles was the company's first production, initially mounted with Australian Theatre for Young People in 2013. It was then invited to La Boite in Brisbane the following year with the same cast apart from Snape, who was touring with Bell Shakespeare. Now, the complete original cast has been reassembled to go on tour in 2016.

In 4000 Miles, Leo, played by Multari, is a 21-year-old from St Paul, Minnesota, who suddenly turns up unannounced in New York at 1am at the Greenwich Village apartment of his 91-year-old grandmother Vera (Diana McLean).

"He hasn't seen her in many years and they're worlds apart," Multari says.

"Leo is Midwestern and very hokey, he's had a stiff upbringing and has a smiley way of looking at everything. He's a huge contrast to his Jewish grandmother who's very nervy and full of heart. The way they interact together is hilarious and often heartbreaking."

At first, it seems Leo – who's bicycled across the country – just needs a place to crash for the night, no questions asked. But his stay becomes a longer one and as they discover more about each other, the old woman and the young man turn out to have a lot more in common than they thought – and not just their shared left-wing politics.

And why has Leo come all this way after all this time? Without giving too much away, there's been a huge upheaval in his life and New York is where his sometime girlfriend (Snape) is studying. Also coming into the story are two characters played by Aileen Huynh: Leo's adopted sister and a young woman he meets in a bar.

Although he's playing a character nearly a decade younger than himself, Multari says that isn't a problem.

"I never get cast playing my age, I always get cast much younger," he says. He notes as an aside that McLean is considerably younger than her nonagenarian character before continuing, "Having a bit of life experience definitely helps in playing Leo – the role is one of the most demanding I've played ... my character doesn't really leave the stage."

But it's not just the role's length that's taxing, it's the emotional depth of it. Without giving too much away, Multari says Leo is trying to deal with terrible grief.

He says Herzog drew on some of her own feelings and experiences in writing the play and those of people she knew and he did the same in playing the character, drawing on memories of bereavement and loss.

"I've attended my fair share of funerals and experienced grief."

He also remembered one incident from when he was a teenager that affected him deeply even though nobody died, when he was among two carloads of friends going out to celebrate a birthday.

"I was in the car in the back, I was supposed to be in the one in front," he says. That front car had an accident and rolled a few times, before stopping upside down and injuring those inside.

"One of them was in hospital for a couple of months ... that could have been me."

It was a stark reminder of the fragility of life and how suddenly luck can change.

But while there's a serious side to the play, he wants to emphasise its warmth, humanity and its humour, especially embodied in Vera.

"She's a hilarious character," he says – but a three-dimensional figure, not shallow or stereotyped. .

Multari, a self-described "Sydney boy born and bred", says there wasn't any opportunity to study drama or even do a play at his school, Marist College, but a chance encounter with Adam Scown, a boy in his year who would become his best friend and who is now a choreographer in London, changed his life.

"I was walking past and caught him tap dancing – at an all-guys' school! – and started quizzing him."

Scown, he discovered, was studying dancing, acting and singing outside school and he became interested, taking up acting lessons and later throwing himself into the Drama Society while studying arts and international studies at Macquarie University.

"In three years I did pretty much every single show there."

And from there he went on to work professionally as an actor with credits including the TV series Kid Detectives and Dance Academy, the feature film Circle of Lies and the plays The Laramie Project (Sydney Theatre Company), The House of Ramon Iglesia (Old Fitzroy Theatre) and References to Salvador Dali Make Me Hot (Griffin Theatre).

And, of course, there's 4000 Miles, now on a three-month tour. It's the first show for his own company and the first time he's come to the Canberra region professionally.

"There's empowerment in creating your own work and in getting a team of people you believe in," he says.

"You have a lot more creative power as a producer; it's your vision being realised."

As for the company name, MopHead, it came out of a university nickname his producing partner gave him when they were at university when she "saw this great mop of hair staring at her", he says.

"It stuck."