It’s a strange time to be releasing a film in cinemas. But for director Shannon Murphy, whose debut feature Babyteeth opens across Australia later this month, the current crisis has connected with her achievement in a way she didn’t expect.

“The timing actually seems more emotional in a way,” she says. “The themes in Babyteeth – of cocooning around the family during a crisis – feel kind of more relevant now.”

Babyteeth is about a seriously ill Sydney teenager, Milla (Eliza Scanlen), who falls in love with a small time drug dealer, Moses (Toby Wallace), who’s seemingly only interested in her for her meds. Her parents, Henry (Ben Mendelsohn) and Anna (Essie Davis), think he’s exactly the wrong guy for their musically gifted daughter. Milla’s time is running out, though, so she grabs her first love with both hands and holds tight.

The screenplay is by Rita Kalnejais, based on her stage play of the same name. It’s a classic coming-of-age story in some ways, but manages to avoid cliches, and never tries to smooth the rough edges of its damaged characters.

“So much of my excitement came from the challenge of the tone of the piece,” says Murphy, who’s previously made several short films and directed two episodes of the acclaimed TV show Killing Eve. “It’s such an unusual mix of very, very deep and dark comedic sensibilities … with a very heavy story. But it also felt very Australian to me. I just knew it could become a classic Australian film if we got the dysfunctional family right.”

One of the major challenges, she says, was casting the four central characters.

“Essie and Ben were a dream couple for the parents,” says Murphy. “I just knew they would be excellent together. They’d never worked together before, but they always wanted to, so that was a really nice opportunity. And we gave Ben a moustache, which he was really excited about too.”

Murphy auditioned several actors for the two younger leads, choosing Wallace as Moses in part for his ability to keep the focus on his co-star.

“Then with Milla, that just took a long time because I was trying to work out exactly who Milla should be,” she says. “But Eliza has got such an extraordinary range and is also really fearless about, you know, shaving your hair and doing all the incredible hard work that goes into learning how to play the violin.”

While Babyteeth is a film about teens, it’s not made for teens. Which, paradoxically, makes it perfect viewing for them.

“Teenagers don’t watch teenage films, they watch adult films,” Murphy says. “That’s the whole point of being a teenager. So while I was making something that was not geared towards teenagers by any means, I wanted to feel like I’d honoured them so that if they did watch it, they would feel they had been really well-represented. I think it’s really important to give teenagers the credit that they deserve.”

Kalnejais did much of the research for the film while writing her script, but Murphy and the production team also contacted Canteen, an Australian organisation that supports teenagers with cancer, to gain a better understanding of the characters.

One thing that stuck with Murphy: she learned that when young patients relapse, their parents often revert to behaving as they did when their child was first diagnosed.

“The child’s getting older, but they’re being treated younger,” says Murphy. “It’s something that we paid attention to quite closely. It’s a protective mechanism to the parents, but it’s a very frustrating thing for teenagers.”

Babyteeth is not overtly antipodean – there are no sweeping shots of the Sydney Harbour Bridge, for example – but the film feels distinctly Australian. Part of that is thanks to Murphy’s direction and cinematographer Andrew Commis’s vivid, colour-charged visuals, but the sound also triggers nostalgia.

“I wanted to really focus on some Australian things that I’ve always found fascinating … like the crazy sounding birds and insects in the summer,” says Murphy. “Every day on set everyone was like, ‘Oh my God, what a nightmare for post-production,’ but I kept all of that in there because I really loved it. It’s so raw – it makes it feel almost like a documentary.”

Babyteeth debuted at last year’s Venice Film Festival, where Wallace won the Marcello Mastroianni Award for Best Young Actor or Actress. “Venice was the first time we realized that we had made something special,” Murphy says. “We had honestly finished the film like a week or two beforehand, and we were just so excited to be there.

“We walked into the [first press screening] and it was a very serious room and I was like, ‘Oh, god, is it just because they didn’t like it? Or is this because they did like it? Or is it just because they’re Italian? What’s going on?’”

The response to the film was overwhelmingly positive, though, with many in the audience tearing up. Murphy teared up on the panel, too.

“That’s what’s been really interesting about the response everywhere,” she says. “It’s one of those things where when people come out of the cinema, they just kind of look at you and put their hand on their heart and make a connection. It’s what you dream of, really … It’s been really beautiful.”

Babyteeth will be released in Australian cinemas on July 23.

This article is produced by Broadsheet in partnership with Universal Pictures.