The soft-spoken 31-year-old had been struggling to get one of his scripts produced since he graduated from the American Film Institute in 2010.

He made a few shorts that got some attention, but he was quickly burning through savings and starting to get bitter about his chosen industry. Hereditary was born out of this cynicism.

"I endeavoured to write a horror film because I figured it would be easier to get made," Aster says.

It wasn't a bad strategy. Horror films are one of the few solid financial bets in the unstable business of making movies no matter what the quality, but even more so when they're good (think: Get Out, It, A Quiet Place).

"I love the genre, I love what it can do but I feel like so many are produced so cynically and most of what comes out is not very good," Aster said. "I thought, 'What do I want from a horror film and how do I make something more substantial?"'

For Aster, that meant making sure people care about the characters: Annie Graham (Collette), an artist whose mother dies at the outset, her husband Steve (Gabriel Byrne), their son Peter (Alex Wolff) and daughter Charlie (film newcomer Milly Shapiro, who won a special Tony honour at age 10 for her role in Broadway's Matilda).

"I wanted it to become a nightmare in the way that life can feel like a nightmare when disaster strikes – especially in succession," Aster said. "All the horror elements are established in the first hour. Instead of these people serving as devices for the horror, the horror is always growing out of them and their experience and what they're suffering through."

The script came to Collette after she'd just told her agent she didn't want to do anything heavy for a bit.

"The murky, heavy stuff started to accumulate and I just wanted to make comedies and then he sent this and I was like, "Aww ... [Ari's] a brilliant writer and it was just undeniable ... I just had to," says Collette

A24, the studio behind Hereditary, Moonlight and Lady Bird, has already agreed to make Aster's next film too, which he'll start shooting later this summer – another genre film about death and strange happenings, this time in a remote Swedish town with "unique midsummer traditions".

"Filmmaking has become so safe and it's so contrary to what people really thrive on and yearn for, because ultimately they want an original voice, they want a strong, clear voice," Collette says. "I'm really excited to see Ari's work in the future. He's the real deal with a clear, strong, exciting vision. He's so talented."

Hereditary opens this week

AP