At the heart of Netflix’s latest big swing at prestige movies is an extremely precocious 13-year-old. Okja, the story of a girl named Mija palling around with a massive superpig in a whimsical mountain setting—a fantastical friendship in the vein of classics like My Neighbor Totoro—stars actress An Seo Hyun in the main role. She’s a bundle of fierceness and unrattled stoicism in a high-concept film replete with madcap plot points, the kind we’ve come to expect from celebrated director Bong Joon-ho and his top-tier talent (Tilda Swinton, Jake Gyllenhaal, Paul Dano). Though Seo Hyun was only 11 when she was cast (and 12 when she filmed), she holds our gaze in the palm of her hand. She’s a bottle-rocket talent and a surprisingly adept action star, someone who will sear a lasting impression on anyone who watches Okja once it’s available to stream, or see in limited theatrical release, on June 28.

In real life, Seo Hyun is petite and polite, with long bangs skirting her eyes. She speaks Korean, her first language, during interviews, but there are occasions where she happily blurts something in English to really convey her point—like when she’s talking about Tilda Swinton. The Oscar-winning actress was kind and protective of the young star on set, Seo Hyun’s translator explains, even taking her to see Finding Dory when they had some free time.

“I loved it,” Seo Hyun gushes in English.

In fact, all of her co-stars were warm and protective, she says. When they filmed certain scenes in New York, Paul Dano took her to see a musical. Jake Gyllenhaal sent her a black luggage set as a wrap gift. Director Bong Joon-ho gave her near-total control of her character, which, for an actor, is one of the greatest gifts of all. When she was cast, Seo Hyun quickly rattled off a number of ideas to the director for what motivated Mija in certain scenes, to the point where she was even illuminating ideas to Joon-ho, who created the character and wrote the script. “Oh, this is why she does this,” she recalls the director saying. In the script, there was “an idea of who Mija was, [but] it was still kind of in the dark,” she says. Seo Hyun gave it the spark of life.

In the film, Mija is a quiet girl living in beatific mountains with her grandfather and Okja, a superpig gifted to her family by a livestock company called the Mirando Corporation, led by a slightly manic woman named Lucy Mirando (Swinton). But after a few idyllic years, the company decides it’s time to take Okja back and make him serve the purpose they bred him for, sending along deranged zoologist Dr. Johnny Wilcox (Gyllenhaal) to pignap him. A fearless Mija immediately goes after them, aided along the way by an extremist group called the Animal Liberation Front, which is led by a man named Jay (Dano).