K-Drama Review - S Line

The Cannes Winner and highly anticipated thriller Korean Series ‘S Line’ starring Lee Soo Hyuk, Lee Da Hee and Oh My Girl’s Arin has recently finished airing leaving viewers in a shock and with many emotions. The drama revolves around mature and sensitive themes of societal prejudices, sex, secrets and shame and is one of the bold and provocative K-drama series of 2025.

The drama that deals with stereotypes just to break it when it comes to the genre of K-dramas.

What is the plot of S Line ?

Adapted from a webtoon of the same name, written by Kkomabi and directed by Ahn Joo-young the six-episode fantasy thriller is based on mysterious phenomenon of people seeing the S Lines, red lines that connect sexual partners. The plot revolves around a girl named Shin Hyeon Heup (played by Arin) who has the ability to see the S Lines since birth. This forces her to relive the most traumatic moment of her childhood witnessing her mother murder her father before vanishing without a trace. These mysterious red lines reveal the forbidden, often sexual connection  between the people. Haunted by what she sees Hyeon Heup isolates herself until a string of unexplained deaths begin plaguing her neighborhood.

That’s when she crosses paths with a detective named Han Ji-wook (played by Lee Soo-hyuk) leading the investigations into these mysterious deaths and is burdened with an overwhelming number of red lines hovering over his head.

Unbeknownst to him his niece is close friends with the same girl, and has unknowingly come into possession of the glasses that transfer the same disturbing ability to see the cursed lines.

Then there is Lee Gyu-jin (played by Lee Da-hee), a seemingly perfect, flawless homeroom teacher- clean, composed and with not a single red line on her head. But beneath the spotless surface lies a secretive character with not so clear intentions.

The impactful performances of the cast bring the characters to life.

Theme of the drama 

‘S Line’ is more than a psychological thriller. It’s a sharp, unsettling, social experiment laid bare. The red lines aren’t just usual effects but emotional detonators that reveal the fragility of relationships that shatter trust. The show drags this hypocrisy into the light and forces the viewers to have a close look. 

Despite being a short drama of six episodes ‘S Line’ manages to keep the viewers intrigued and hooked with revealing twists till the very end. However, the drama does have some loopholes and leaves many questions unanswered. The series also delves into some of its darkest territory with sexual assault, incest, depression, school violence, bullying, intentional homicide, adultery, nudity and even unsettling hints of necrophilia. These themes can be deeply triggering and the absence of clear content warnings has been a major point of frustration for many viewers which has not only dampened the drama’s reception but also fueled the polarized and often cynical feedback it continues to receive.

Strong performances

The star-studded cast still manages to deliver their best performances. Lee So-hyuk as detective Han Ji-wook with his deep voice and charisma shines in the role of cocky, not-so perfect, aloof but handsome detective. Though he is dedicated cop with a deep sense of justice and loves his niece but is clueless when it comes to taking care of her who gets bullied in school.

Lee Soo-hyuk as Han Ji-wook

Arin as Hyeon Heup delivers extraordinary performance and leaves viewers captivated. His portrayal of her character from being recluse and cooped up inside the house to finally accepting herself and gaining the courage to live her life makes viewers hold their breath and empathize with her.

Oh My Girl's Arin as Hyeon Heup

Lee Da-hee as Lee Gyun-jin the homeroom teacher with mysterious aura and no ‘S Line’ serves as a surprise element. She showcases impeccable command over her emotional and subtle micro expressions with such precision that allows her to seamlessly embody the role of a duplicitous antagonist.

Lee Da-hee as Lee Gyun-jin

International Success

At the 8th Cannes International Series Festival in May 2025 where ‘S Line’ premiered its original soundtrack, won the Best Music award , a recognition given to the music director Lee Jun-oh and a proud milestone for Korean entertainment industry. The OST ‘Between the Lines’ by Park Ye-ni who also played a cameo as Hui Won in the series,  flows seamlessly with the drama’s tone, deepening its emotional resonance.

The star cast of 'S Line' at 8th Cannes International Series Festival.

Overall reception 

The drama’s exploration of shame, power dynamics, the pressure of not fitting in, societal expectations, sharp and harsh judgements would probably hit different at many levels for audiences who understand and have faced such situations. In a world where social media puts our private lives under microscope, imagine if our deepest, most intimate relationships were on full display for everyone to see. What captivated the viewers is not the only the situations but the choices and the resulting consequences that characters face prompting them to ponder what might have been different and what choices could have spared the character from their grim outcomes.

A still from the series.

From prejudice and stereotypes to mockery, cruelty, desperation, shame, madness, grief and disbelief- this K-drama embraces it all. It drives home the truth that what’s seen can’t always be real and some truths are best left in the dark. One way or another ‘S Line’ will push you to rethink everything you believe about privacy, relationships and complexities of human nature.