Steven Yeun has the kind of mischievous smile that seems to be concealing some sort of secret. In person, it’s a smile of immediate familiarity, flashed as though speaking to a friend who shares a secret language—and in a way he and I do, occasionally speaking Korean to each other while his non-Korean rep sits just a few feet away. “I’m a FOB,” Yeun says, laughing, after telling me where in Korea he grew up (he was born in a district called Bongcheon-dong in Seoul) and when he moved to the States (Yeun’s family relocated to Troy, Michigan, in 1988, when he was 4—“right before the Olympics in Seoul”). Yeun is in New York City this October morning for the New York Film Festival premiere of the South Korean drama Burning, which opens in NYC on Friday and in L.A. on Nov. 2. In Lee Chang-dong’s film, Yeun frequently deploys his trademark impish smile—but in this case one that implies something sinister.

Over the past 20 years, director Lee has been making challenging melodramas like Oasis (2002), Secret Sunshine (2007), and Poetry (2010), to quieter acclaim than his more internationally renowned countrymen Park Chan-wook (Oldboy, The Handmaiden) and Bong Joon-ho (Snowpiercer, Okja). Lee’s films lack the genre sensationalism or the American accessibility of the aforementioned directors, instead favoring brutal emotions and long runtimes. Burning is South Korea’s third official Oscar submission directed by Lee, after Oasis and Secret Sunshine, but the first of his that utilizes a Korean actor familiar to the American public. Burning set a Cannes record earlier this year for highest jury score (3.8, beating Toni Erdmann’s 3.7), but despite an established reputation in global cinema, Korea has still never received an Oscar nomination. “It seems like a lot of pressure, I’m trying not to think about it,” Yeun says regarding his, Lee’s, and, really, Korea’s chances at the next Academy Awards.

Burning is arguably Lee’s most watchable film to date, and Yeun turns in his career-best performance as Ben, a Korean Patrick Bateman type, only less explicitly psychopathic. An extended adaptation of Haruki Murakami’s short story Barn Burning, based on William Faulkner’s story of the same name, Burning follows a quiet young man named Jong-su (Yoo Ah-in), who reconnects with his old classmate Hae-mi (Jeon Jong-seo) and starts to fall for her. But when a well-traveled, charismatic rich guy named Ben comes into the picture and swallows all of Hae-mi’s attention, Jong-su starts to chip away at Ben’s flawless veneer.

There’s a brilliant ambiguity about the characters in Burning; Ben is always just unsettling enough, while Jong-su’s suspicions border on jealous paranoia. Ben’s disquieting nature is subtle, signaled in Yeun’s smile, which in Burning sometimes breaks into a laugh that could send a chill down your spine. When Ben is making pasta for Jong-su and Hae-mi in his posh apartment, he says cooking is like making an offering to himself, implying his self-perception as a godlike character. Jong-su’s misgivings reach an apex when Ben shares his peculiar hobby, from which Burning takes its title: He likes to set greenhouses on fire and watch them burn—for fun.

His role in Burning is a decidedly different turn for Yeun, who got his break playing a beloved, heroic character. Yeun’s six-year stint as Glenn Rhee on The Walking Dead turned him into a recognizable, bankable Asian American actor who’s since been gracefully toeing both sides of his background. In the past two years, he has appeared in films like the Netflix original Okja (as an English-speaking Korean American) and in the radically American feature Sorry to Bother You, from director Boots Riley. In fact it was Okja that led Yeun to Burning—Bong Joon-ho connected Yeun with director Lee. In Bong’s film, Yeun plays the Animal Liberation Front member called K, a Korean American who comically muddles the English-to-Korean translation of his group’s mission. (For the movie, Yeun purposely made his Korean sound worse than it actually is.) In Burning, Yeun tipped the scale over to full Korean to play Ben—though the character does have an Americanized flair. “I’m happy to be some weird, very fortunate anomaly to bridge some gaps,” he says. “I’m not mandated to do those things but the work I find ends up happening that way. Okja was very obviously that way and Burning became an entry point for people who wouldn’t have seen me.”

Burning feels very much like a Korean movie, with its jarring juxtaposition of urban and rural settings and probing critique of Asian masculinity. But it also contains a very American anxiety—not only in the brief flash of President Trump on the news in an early scene, but also in the nouveau-riche aspirations of Seoulites. Ben is clearly not your average Korean—you can tell just by his name. His “otherness” is also apparent in his carefully crafted dialogue, a nuance which may get lost for non-Korean-speaking viewers. While the other characters speak colloquial Korean, Ben’s is alarmingly elegant, as though diligently studied from a textbook—the kind of Korean one would speak to convince others of their elite status. If Yeun’s Korean was clunky in Okja, in Burning it sounds perfect—too perfect, even; Yeun wonders whether his Korean is so unnaturally advanced that Korean Americans who aren’t fluent in Korean will think he’s butchering the language. Native speakers would be impressed, though. “I’ve heard people say Ben’s Korean is better than Jong-su and Hae-mi’s Korean,” he says. “But that’s because theirs is more natural whereas Ben is more exacting with his words. Those are all specific directions and decisions we both made. Director Lee wanted to juxtapose this person being unequivocally Korean but also show that there’s something weird about him that you can’t explain. And he knew that people knowing my face might create that dissonance. He’s a genius.” It’s true; you may watch Burning and feel like you know Yeun from his past roles, but Ben draws out something inexplicably strange from him, and you feel it every time Yeun is on screen.

To familiarize himself with the script, which is quite a mouthful, Yeun had someone record his lines so he could listen back and read along because his reading in Korean is a bit slow—he now recalls it as an “agonizing experience.” Lee brought Yeun to Korea a month before shooting, and during that time the actor became more comfortable with the language. Lee, who also happens to have taught language in high school, helped Yeun drill down on the script. During this process, Yeun said he would dissect the dialogue and home in on the root of every word, opening up a whole new appreciation for Korean. He tells me to look at the word 자신감 (ja-sin-gam), which is translated into English as “confidence,” for example. Dissected, the word literally means “sense of self.” “It’s juxtaposed to how Koreans live life,” he says. “Our confidence comes from other people’s perception of us when the word in and of itself tells you it’s about how you feel about you.”

Yeun brings up one particularly mysterious word he had to familiarize himself with: “동시 존재” (dong-si jon-jae), translated as “simultaneous existence.” It comes up halfway through the movie in a critical scene, when Ben starts to reveal his true self to Jong-su. After smoking a couple of joints—provided by Ben, as another sign of his worldly exoticness, as marijuana is still taboo in Korea—he tells Jong-su about his hobby of burning down greenhouses, how he can make something disappear as though it had never existed in the first place. He justifies his actions with the concept of “simultaneous existence.” For example, rain may fall and cause a flood that kills people, but by nature, rain doesn’t judge what is right or wrong. “The morals of nature are like simultaneous existence,” says Ben. It’s a confusing line but one that informs the many dualities in the film. “In a way the script is almost saying everything,” Yeun says. “So [Lee and I] didn’t try to understand Ben from a material, physical level, but from a deep, philosophical one.”

It is a challenging, layered portrayal that brings out the best in both director and actor. “I personally don’t think I’ll ever be able to do another Lee Chang-dong film,” Yeun says. “Not because I don’t want to or because he wouldn’t want me to, but I found the perfect role with a director that could use me in that situation.” With Burning’s critical acclaim in Korea and the U.S., Yeun’s star power is rising in both of his home countries. In America, he’s already achieved that coveted Internet Boyfriend status—an extension, perhaps, of his loyal persona on The Walking Dead. He’s handsome, genuinely seems like a nice guy, and feels like one of those relatable celebrities. Meanwhile, I also know Yeun is becoming a big deal in Korea because all of a sudden, my parents, who live there, are big fans. But while Yeun may look like a Korean celebrity, he doesn’t quite walk like one, which is part and parcel of why he is so effective in Burning. His natural state brings a certain Americanness to the film—he says director Lee recognized a hardness in his bones that sets him apart. “Maybe that’s what director Lee was talking about,” he says. “My Americanness is very loud. And as much as I’m able to speak the language, and culturally kind of weave into it, there’s something about me that’s like, ‘That guy’s not from here.’ And that’s the first thing that catches people’s eye.” If not that mischievous smile.