Disney+’s new thriller series “Hyper Knife” delves into the intense, dark conflict between two brain surgeons, setting off a chain reaction of obsession, murder and revenge. With its incisive social commentary and narratives that push the boundaries of surreal fear, “Hyper Knife” promises to redefine the genre with its chilling portrayal of an ambition that turns into madness.

“It feels like a brutal fairy tale, a series that explores the relationships and conflicts of those driven to madness by their obsession with brain surgeries,” said director Kim Jung-hyun during a press conference held Monday at the Conrad Seoul hotel in western Seoul.

“We focused on revealing their personalities and the evolution of their relationship. Se-ok is an energetic, emotionally expressive character, while Deok-hee’s calm demeanor is used to highlight the two’s inherent conflicts in numerous ways,” Kim added.

Actor Park Eun-bin, known for ENA’s 2022 drama “Extraordinary Attorney Woo,” takes on the role of surgeon Jeong Se-ok, a practitioner who becomes consumed by a manic obsession with brain surgery, later resulting in violent behavior. Meanwhile, Sul Kyung-gu, recognized for films like “A Normal Family” (2023) and “Memoir of a Murderer” (2017), portrays her mentor, the unyielding and cold-hearted doctor Choi Deok-hee.

When mentor Deok-hee notices Se-ok’s violent tendencies and her inability to control her emotions, he forbids her from performing surgeries, leading her down the path of illegal procedures as a shadow surgeon. Then, when Deok-hee himself needs brain surgery, he turns to the talented Se-ok. The mentee’s emotions begin battling between a desire for vengeance and the perfectionist’s quest for flawless surgery.

“We’ll be showing many uncontrollable moments,” said actor Park.

“It was all incredibly exciting because we were venturing into a genre and character type we'd never explored before, and above all, Se-ok is a character who, together with Deok-hee, delivers a raw, invigorating dynamic.”

Reflecting on his own role, actor Sul described his character as “a man who lives solely for his own self-importance, exuding authority and earning respect. Yet, he appears awkward and uncertain about how to interact with others.”

“He’s the cold-hearted type who even casts aside his one cherished disciple, Se-ok. In the latter stages of filming, I aimed to introduce variations in his confrontations with Se-ok, revealing not only his logical and cold-blooded side but also a somewhat clumsy, almost childlike vulnerability,” Sul said.

Supporting these leads are Yoon Chan-young and Park Byung-eun. Yoon, known for Netflix’s 2022 zombie thriller “All of Us Are Dead,” plays Seo Yeong-ju, while Park Byung-eun, recognized for another Netflix zombie series “Kingdom” (2019–), portrays Han Hyeon-ho. Both characters support and side with Se-ok.

“Yeong-ju always stands by Se-ok’s side,” said actor Yoon. “Even though he knows her secrets, he continues to protect her, always prioritizing Se-ok over anyone else.”

“Hyeon-ho only sees Se-ok’s good qualities without truly knowing her,” Park Byung-eun said about his role.

While the series delves into heavy themes, such as illegal surgeries, medical ethics and even murder, the director and cast emphasize that a psychological battle, shaped by character dynamics and relationships, is at the core of the storyline.

“This series revolves around the raw, urgent tension between Deok-hee and Se-ok, as well as the intricate roles of those around them,” Park Eun-bin said. “Viewers may struggle to understand the characters initially, but as the story progresses, they’ll start to see what these characters are trying to do and show. I hope viewers experience the emotional shifts along the way.”

“There probably has never been such a mentor-disciple dynamic before,” Sul said. “Although these two harbor a mutual, intense hatred, there’s also a striking similarity between them, and I hope viewers will pick up on the subtle details and emotions interwoven throughout their relationship.”

Portraying characters with obsessive traits that set them apart from ordinary people and roles that demand expert knowledge required the cast to engage in extensive study and research beyond merely acting.

“I had never even seen brain surgery before,” Sul said.

“In preparation, I studied by watching videos with a neurosurgery professor, observing how surgeons enter the operating room and handle equipment, all in the name of realism.”

“I drew on materials I had compiled during my college days studying psychology — particularly on mental illnesses and the traits of characters with antisocial personality disorder — for this project,” Park Eun-bin said.

“Because brain surgery is such a detailed and delicate procedure, this series isn’t just about the stories of hospital doctors. It’s about exploring the psychology behind a broader, complex world,” said director Kim.

“In that sense, the brain and its inherent sensitivity perfectly complement the narrative.”

Disney+’s upcoming thriller series “Hyper Knife” will debut on Wednesday.

BY YOON SEUNG-JIN [yoon.seungjin@joongang.co.kr]