LOS ANGELES — Toni Collette wasn’t looking for darkness when “Hereditary” came calling. But when the darkness found her – in the form of the unnerving saga of the Grahams, an American family haunted by tragedy, mental illness and perhaps something supernatural – the opportunity was too delicious to pass up.

“I wasn’t interested in doing anything heavy, but I picked up the script and I couldn’t stop reading it,” the Australian native, 45, explained one May morning, slipping into the same busy Westside eatery where, just over a year ago, writer-director Ari Aster convinced her to take the plunge and play a woman who begins to unlock cryptic family secrets after the death of her own estranged mother.

The result, a claustrophobic chiller that distributor A24 released on Friday, features one of the most dynamic and memorable performances of Collette’s career, in what critics are calling the scariest film in years.

Collette’s Annie Graham is many things. A miniatures artist who fills her home studio with dioramas of her own life, she re-creates memories as a means of reclaiming control. A mother of two with a strained relationship with her own mom, she is overprotective of one of her children and coldly resentful of the other. And when the unthinkable strikes, she struggles to cope with a sense of powerlessness that gives way to relentless dread as Aster spins his crumbling, nightmarish narrative.

The film has had audiences cowering in terror since it premiered in January at the Sundance Film Festival, jangling nerves with its potent visceral scares and leaving viewers rattled with the deeper psychological concerns baked into its DNA.

“There’s this trend especially among American family tragedies, or family dramas, where people suffer a loss, and they go through a very tumultuous time together, but ultimately it brings them together and strengthens their bonds,” explained Aster. “That’s just not always what happens. Sometimes something happens and it takes one person down in a family, and it ends up taking the family down. I wanted to make a film about that.”

Gabriel Byrne, Alex Wolff and newcomer Milly Shapiro co-star as the husband and children, respectively, whose lives are also upturned by revelations after the passing of the eccentric family matriarch; “The Handmaid’s Tale” Emmy winner Ann Dowd also excels in a supporting role as an overzealous stranger from a support group for grief counseling.

But at the center of “Hereditary”s quietly raging, rapidly crescendoing storm is Collette, delivering a powerhouse performance so riveting it could – and, some pundits say, should – earn her awards-season attention. (She has one Academy Award nomination, for “The Sixth Sense” in 2000.)

“It’s pretty crunchy,” she laughed, describing the complicated dynamic that emerges between Annie and her family, making for razor-tipped exchanges at the dinner table. “My character had such an unfortunate relationship with her own mother, much of her own ability to mother her own children and to be selfless is difficult for her. And I think part of being a present mother is learning how to be somewhat selfless. But there are so many idealized myths about what motherhood should be, and I love that both my character and the character of my mother have nothing to do with these myths.”

On paper “Hereditary” might have seemed somewhat of a risk, even with A24 onboard early, being a strikingly ambitious piece of genre filmmaking and Aster’s first feature after helming several provocative shorts at AFI.

Collette too admits she isn’t one to watch scary movies. “But it isn’t simply a horror film. It’s quite natural and emotionally raw and honest. For those qualities to blend in a film like this is really unusual, and I loved that.”

To prepare, Aster didn’t screen horror classics for his actors but instead pointed them to searing family melodramas, films like “Ordinary People,” “The Ice Storm,” and Mike Leigh’s “All or Nothing.” Although Aster knew he had to nail the horror movie moments in “Hereditary,” his intention was to cleave deeper than superficial jump scares.

“The idea was to create a film that collapsed under the weight of its own emotions,” he explained. “It’s so packed with extreme feelings that the fabric of the film tears open, and the film itself goes crazy.”

Collette had her hesitations. Over the years the veteran actress realized that slipping into the skins and psyches of others was a job that sometimes came home with her. She has two children, now ages 7 and 10, with musician husband Dave Galafassi. Did she really want to volunteer to live inside a punishing nightmare about motherhood, trauma, compulsion, and grief for the duration of filming?

“I kind of know immediately if I want to do something or not; it’s very apparent. I was looking for reasons not to do it,” laughed Collette, who had to be sure the emotional toll would be worth it. “So I thought I’d speak to (Aster) and see if he was a (jerk). But he’s actually the kindest, most humble, dear human being. It was so evident that he knew exactly what he was doing.”

The two clicked over the material. Thoughtful and soft-spoken with a rebellious inclination to defy convention – and unimpressed with most contemporary horror – Aster had already spent years preparing his vision for “Hereditary” and had a detailed shot-list drawn out, firmly plotting out every frame and composition of the film. And he had a big ask of Collette.

“I had loved her work since ‘Muriel’s Wedding,’ and Toni is always great – but I also realized I had never seen her chew apart the scenery in this way, and I just knew that she could,” Aster recalled. “I think I said, ‘I need a kamikaze performance – I need you to jump off the deep end.'”

She took the role, bringing the character of Annie Graham to life. During the week she played out Aster’s tragic tale on a meticulously custom-crafted set in Utah alongside Byrne as Annie’s psychoanalyst husband, Wolff as their teenage son Peter, and Shapiro as Charlie, the 14-year-old daughter with a knack for crafting morbid totems and a mysterious connection to her dearly departed grandmother.

“I think there are some jobs where you egg yourself on and allow yourself to get really caught up in it, but with this I was pushing it away constantly until it was time to shoot. Until they called ‘Action!’ I just didn’t want to really think about it,” Collette said, sipping green tea to combat the overcast day.

Was that part of her methodology? She laughed.

“I think it’s just called survival.”

On weekends Collette would return to Los Angeles, decompressing on the flight home, leaving the heaviness in the air across two states. “I think it was both good for me to have that solitude during the week and also to have a complete departure from the experience that I was embedded in on the weekends,” she said.

Often while discussing “Hereditary,” she gives generous credit to Aster’s writing. “The script was very clear, but there was also room for interpretation,” she added. “It felt very real; it felt heartbreakingly real. It (made) me appreciate Ari so very much because he just understands what it is to be human.

“But also kind of worry about him,” she added half-jokingly, “because, why does he have this information?”

Collette brings a relatable skepticism to Annie as she’s drawn deeper toward buried truths, anchoring some of the film’s most horrific moments in a narrative that doesn’t depend, as many horror films do, on gory shocks. One of “Hereditary”s most disturbing images is simply a close-up on her face, twisted in a drawn-out scream, her mouth agape in grief and shock.

Collette describes the scene as “stomach-turning” but delights in the thought that it might terrify audiences for years to come. She watched the film with an audience for the first time recently, which gave her a kick.

“It was really fun,” she said, her eyes lighting up. “It really made me laugh. There is some levity to this movie, and I think there has to be because it is really very, very dark, and it doesn’t let up; the sense of dread and suspense is always there.”

A curious performer, she says she always watches her own films to see how the magic of moviemaking comes together in the end. One exquisitely timed sound effect in “Hereditary,” she reports, made her jump in her seat, even though she was the only actor onscreen. “I knew what was happening and I still jumped!”

Collette’s intense commitment to character and ability to access a spectrum of relatable human experiences have long been present in her work, from the ABBA-obsessed misfit of her 1994 breakout film, “Muriel’s Wedding,” to that Oscar-nominated turn in “The Sixth Sense,” in which she played another mother dealing with supernatural mysteries that lay just a hair’s breadth beyond comprehension.

Her performance in 2006’s “Little Miss Sunshine” earned a Golden Globe nomination, and the following year she dove into the lead role on Showtime’s “The United States of Tara,” for which she won a Golden Globe and an Emmy playing a housewife and her multiple “alters” living with dissociative identity disorder over the course of three seasons.

Lately she’s been working at a breakneck pace, and had half a dozen feature films premiere theatrically or at festivals in 2017 alone. But “Hereditary” stands out from the pack.

Rewarding as Collette describes it now, a year after filming, making “Hereditary” was nonetheless a draining experience – part and parcel with the job, she says.

“A lot of this is so intensely emotional, and my job as an actor is to make it completely transparent and as honest as possible,” she shrugged. “I’ve been to drama school, I’ve been doing this a long time, but ultimately the most important thing is to empathize. In order for the audience to feel it, you need to feel it. It’s all energy. You can’t fake it.”