Even before its official release, the upcoming Korean drama S-Line is garnering international attention for its bold storyline, which blends fantasy, psychological tension, and social commentary.

Set to premiere on Wavve on July 11, S-Line stars Lee Soo-hyuk, Lee Da-hee, Arin, and Lee Eun-saem. The series is adapted from the webtoon of the same name by artist Kkomabi, whose work is part of the acclaimed "Trilogy of Death."

The premise centers around a mysterious phenomenon: visible crimson threads—called "S-Lines"—that connect individuals who have had sexual relations.

These connections become visible through a unique pair of glasses and serve as clues in a chilling murder mystery.

"I've seen these lines since I was born," says Arin's character Hyun Heup in the series trailer, released July 2.

Her ability to see these S-Lines is soon tied to dark events surrounding her classmates.

Lee Soo-hyuk stars as Han Ji-wook, a detective who gets caught up in the messy investigation.

"I just can't understand why they killed them," he says, hinting at the deeper secrets behind the murders.

Lee Da-hee portrays Kyu Jin, a high school teacher who encourages others to wear the glasses despite warnings.

"That's why those glasses are dangerous," Hyun Heup cautions. The tension escalates as bullying victim Sun-ah, played by Lee Eun-saem, begins to uncover horrifying truths through the S-Line.

Already internationally praised, the series won Best Music at the Cannes International Series Festival, also known as Canneseries, becoming the first Korean drama to receive the honor.

The jury commended the emotional score for enhancing the show's impact. S-Line is also just the third Korean drama to compete in the festival's main category, following Mother (2018) and Bargain (2023).

The chilling trailer concludes with the line: "Can you really be sure of what you saw?" — a fitting encapsulation of the show's exploration of perception, intimacy, and concealed trauma.

"S-Line boldly pushes the boundaries of traditional K-dramas," Wavve said in a press release. "It's a rare combination of suspense, social critique, and fantasy that resonates deeply with modern audiences."

The six-episode series will air two episodes weekly over three Fridays—July 11, 18, and 25.

As international curiosity builds, critics and fans alike are hailing it as one of the most daring K-dramas of 2025.