Six people died in a boating accident in Sydney Harbour in 2008 One of them was 25-year-old youth worker Savannah Holloway. Darwin-based playwright and actor Mary Anne Butler, a friend and colleague of Holloway says, "She was an incredible young woman ... When Savannah was killed I just felt really empty. Why her?"

Butler says that having no religious faith she had nothing to attribute the death to and the next year she and her dog, Piglet, climbed into a campervan and made the long drive from Darwin to Sydney. "I needed to do it," she says.

When she came to Sydney Harbour she felt the presence of Holloway and her DNA in the water – and it helped.

"I felt at peace," she says. "It made me feel quite good. What she left the world was a powerful legacy of positive energy."

But the journey was just as important as its ending. Butler drew on her long trek for her theatre monologue Highway of Lost Hearts, which puts a magic-realism slant on her experience.

"Lee Lewis, the director, read the first draft and said it was a metaphor for a country that's lost its heart."

In the play, Mot wakes up one morning to discover her heart is missing from her chest. She has a pulse, she can breathe, but she doesn't feel anything. So she decides to go in search of it, travelling thousands of kilometres with her dog down the Highway of Lost Hearts into the Australian outback - making discoveries about the land, the people who inhabit it and about herself.

Butler's original journey took her to Aboriginal missions and to Woomera, but as well as these less happy places she says she had a lot of positive encounters, too.

"The people I met were really gorgeous. People who live in these little towns are country folk who look after each other."

She says that in some ways the journey healed her and made her realise she had to move on with life.

Highway of Lost Hearts was first performed in 2012 at the Darwin Festival with a repeat season the following year. Now Butler is back on the road, only this time she is touring the show - covering all the states and territories except Western Australia and Tasmania over 10 weeks - rather than making a pilgrimage.

And there's another big difference.

"In 2012 my dog was sick so I took her to the first rehearsal."

This gave the director an idea and at the end of each performance for the first two seasons Piglet would come out and nuzzle Butler. But then she died and Butler does not have a replacement.

"I can't - she was such an extraordinary dog."

Butler's father was a diplomat and the family lived in Canberra between postings. She studied English literature at the Australian National University in the 1980s and became involved in local theatre. She went on to study acting at the Victorian College of the Arts and taught in Queensland before moving to Darwin in 2002 when her then husband got a job there.

"He left in 2007 and I stayed," she says.

Besides the warm climate, she also likes the warm support of the arts community there.

Butler says that audiences respond to the character she plays in Highway of Lost Hearts - sometimes literally.

"People say things back from the audience, there's a fair bit of banter."

She speaks the last line of the play three times. At one performance, when she came to the final repetition, a woman in the audience stood up and said it with her.

"It was really terrific."