Elizabeth Debicki can keep a secret.

Maybe it comes from her stint in the Marvel Cinematic Universe, where she made a memorable appearance as a gold-painted alien in “Guardians of the Galaxy Vol. 2.” Or from dabbling in the world of espionage in AMC’s adaptation of John le Carré’s spy thriller “The Night Manager.” Maybe it’s her elegant appearance, which might be why she is frequently cast as cool and aloof figures, something that started with her breakthrough roles as the alluring but deceptive Jordan Baker in “The Great Gatsby” and a stylish villain in “The Man From U.N.C.L.E.” But to hear the Australian actor tell it, convincing the world she’s an enigma is her greatest performance yet. “One time, Isabella Rossellini said I was mysterious, and it basically made my life because I’ve always wanted to be mysterious!” Debicki says with a laugh. “The truth is, I can’t keep up that act for more than four seconds. As soon as I get to know somebody, that narrative goes away pretty quickly.”

There’s an Australian word — “dagginess” — which Debicki says roughly translates to dorkiness. “Yeah, I’m a big dag,” she admits. “I always have been. I was that kid in school who would always write 500 words more than the assignment required.”

Debicki is calling from Los Angeles, where she’s been quarantining, and quickly proves her dag credentials by geeking out about her lockdown entertainment diet. She just watched Judd Apatow’s “The King of Staten Island,” which she adored. She’s also a huge fan of Trevor Noah, particularly how he’s been handling the coverage of the current protests with intelligence and humor. Asked if she’s been approached to do a comedy, she says, “People don’t approach me — remember the aloof thing?” she jokes. “Even before Fauci, it was always ‘Six feet away from Debicki!’ It’s too bad because I do love smart, fun comedy.”

“Oh, she’s got a great sense of humor,” concurs director Susanne Bier, who cast her in “The Night Manager,” where she says that off-screen, Debicki held her own in a battle of wits with Hugh Laurie. “She’s very good at diffusing her own elegance. It was funny to watch her wearing some gorgeous gown and then realize she left something in her trailer so she’d throw on running shoes and go racing off, still in this beautiful dress.”

Today, Debicki has a unique responsibility suited to her secrecy and befitting that mysterious persona: She is supposed to talk about her new film “Tenet,” without revealing much of anything. Originally slated to open July 14, the film has been pushed back twice due to the coronavirus and is now set to bow on Aug. 12. Because director Christopher Nolan commands his cast and crew to stay tight-lipped about his movies, it’s impossible to guess what’s in store. What has been gleaned from the trailer and early buzz is that “Tenet” features many of his trademarks: an impressive ensemble (in addition to Debicki, there’s John David Washington, Robert Pattinson, Michael Caine and Kenneth Branagh), big-budget spectacle, monochromatic suits and a sci-fi storyline having to do with … manipulating time, we think? The trailer features Washington learning how time can be inverted, with bullets appearing to load back into a gun after being fired.

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Art Streiber for Variety

What Debicki can reveal is that she’s playing the estranged wife of Branagh’s villainous character. She was thrilled to work with Nolan, and the movie is “the kind of experience you want to have when you go to a cinema.” It was filmed in seven countries and ranks as the longest shoot she’s ever been on, dwarfing that of the six-part “The Night Manager” series. And though the budget tops $200 million, Debicki says “every penny goes on the screen.”

“Chris builds everything; he constructs all the imagery piece by piece,” she marvels. “He has this ability to make a film that involves complex thinking and yet make it entertaining and accessible. It’s almost got the feel of an indie set because of the precision — Chris works very fast; time and energy are spent on all the right things there. There is nothing superfluous. It was humbling and collaborative and definitely made me stronger as an actor and probably as a person.”

Ironically, Debicki was almost too good an actor for Nolan to consider at first — having seen her work in “Widows,” he assumed she was American. “I was looking for a very, very British characterization, an English Rose kind of character,” Nolan reveals. So when Emma Thomas, Nolan’s wife and producing partner, suggested Debicki, she had to inform him the actor wasn’t from the States. “Elizabeth’s one of these great actors who, when they’re brought to your attention, you realize you’ve seen them in a lot of things but not realized it’s the same person,” he says. Nolan went back and rewatched her work in “Widows” and “The Great Gatsby,” along with “The Night Manager,” and was struck by her range. “For somebody as striking and interesting to look at as she is, the idea she has a chameleon-like ability speaks volumes to her skills as an actor.”

Debicki insisted on auditioning. “I certainly wasn’t asking,” Nolan says. “There’s a certain level of actor who, as a director, you don’t necessarily want to ask them. But she wanted to. I think it was important to her to know that she could do what I was looking for. And she came in and just blew everybody away. In my mind, she was only confirming what I already knew. What she did with it is far beyond my hopes even.”

While he would never give away anything about the plot (we tried), Nolan will say that he believes Debicki pulled off an incredibly challenging role. “It’s a very difficult character because she has to be extremely vulnerable and put upon, and yet there has to be this strength, this depth, these reserves that come forward,” he allows. “I think that’s very difficult for an actor to pull off without resorting to the unrealistic or resting on the simplistic version of the character arc. She finds a way to play vulnerability and strength at the same time, which is very human and very real.”

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Debicki portrays Jordan in “The Great Gatsby.” Bazmark Films/Warner Bros/Kobal/Shutterstock

For her part, Debicki refuses to confirm or deny fan theories about “Tenet.” She does get a kick out of some of the speculation and hints that ultimately, “people are going to be very, very surprised.”

While she can’t divulge the secrets of the movie, Debicki is willing to remove some of the mystery around herself. She’s the oldest of three siblings, born to a Polish father and an Australian Irish mother. Both parents were dancers into their 30s, a discipline Debicki took up. She was an overachiever in school, describing herself as “tall and gangly.” She mentions feeling out of place everywhere except in academia. “When I was 14, I remember walking into a library and getting physically overwhelmed with possibility,” she recalls. “I would tell people that, and they were like, ‘Ew.’”

She applied to several universities, including law school and theater programs. While on vacation with her family, she received word she’d been accepted to nearly all of them. There was no doubt in her mind: She wanted to attend the University of Melbourne’s Victorian College of the Arts. “I do remember it being difficult for my parents because they were freelance artists and they understood the struggle between doing the art you want and, frankly, finance.”

She started college at 17 and was out in three years. “You’re going to call me an overachiever again, aren’t you?” she laughs. She did a small part in an Australian film called “A Few Best Men”: “I think I have two lines and my character spends the movie trying to find sheep, I kid you not.” But she got to work with Olivia Newton-John and Rebel Wilson, and bought a computer with her first paycheck.

Then came “The Great Gatsby,” Baz Luhrmann’s adaptation of the F. Scott Fitzgerald novel. With Leonardo DiCaprio and Carey Mulligan lending star power, Luhrmann was a   ble to give the role of Jordan, Daisy’s socialite friend, to a new face. Debicki put herself on tape and, much to her surprise, was invited to Los Angeles.

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Debicki and Kenneth Branagh star in “Tenet.” Melinda Sue Gordon/Warner Bros.

It was only her second screen test, and she was terrified of the camera. “I dropped all my lines; we had to do so many takes,” she says. “We had done theater training in school, and I really didn’t know how to adjust for film. I remember the reader was talking incredibly quickly, and I thought, ‘Is this how people talk in movies?’”

Still, Debicki got the part and soon found herself sharing scenes with some of the biggest names in the business. In quick succession she was acting opposite Cate Blanchett and Isabelle Huppert (onstage in “The Maids”), Tom Hiddleston and Laurie (“The Night Manager”) and Viola Davis (“Widows”). She also played a powerful supporting role in “The Tale,” played Virginia Woolf in “Vita & Virginia” and most recently appeared alongside no less than Mick Jagger in “The Burnt Orange Heresy.”

To hear her directors tell it, Debicki thrives on the challenge. Steve McQueen cast her in “Widows” as Alice, who becomes a paid escort after her abusive husband dies. “You can’t bring a lightweight to the party when you’re working with Viola,” McQueen notes. “But great actors like great actors, and they had amazing chemistry.” McQueen also believes Debicki’s background as a dancer helps. “She understands space and the whole idea of how the architecture of a performance is using space and control of the body,” he says. “She has all the skills you could want, emotional and physical. She’s a natural actor.”

Bier says Debicki fit in perfectly on “The Night Manager,” establishing an easy rapport with her co-stars even though she was only 24. “She brought so much depth to the character, more than I expected,” says Bier. “Everything she does is so soulful. Her depth is so striking and why I never thought of her as less experienced than the rest of the group.”

But Debicki says she is intimidated. “I probably hide it well. People probably think I’m cool and aloof, but the truth is I’m panicking and sweating,” she reveals. “That first day on ‘The Maids’ with Cate and Isabelle, I’m honestly surprised any sound came out of my mouth.” Yet she also relishes the opportunity to take what she calls a master class from her peers. “Acting is learned by the doing of it, and you’re only as good as the company you keep as an actor,” she notes. “You need to be in good company to grow, and I’ve been so fortunate to learn from these amazing actors and be pushed by their excellence. With experience comes confidence, with confidence comes recklessness and with recklessness comes art.”

Art has been more important than ever during the lockdown, and when (and if) “Tenet” is released next month, it will be many people’s first foray back into a theater. “Everybody’s taking their own steps back out into the world, and we have to be empathetic,” Debicki notes. “But it’s a very heightened feeling to think the film I made last year may be one of the first things back in cinemas for months.”