What do those red lines represent? S Line plot explained as Lee Soo-hyuk's dark history leaves internet in a frenzy

On July 11, 2025, Wavve released the first two episodes of its newest thriller, S Line. The drama immediately grabbed viewers’ attention for its provocative concept and visually haunting execution. The drama explores a world where hidden s*xual connections are revealed by glowing red threads, called “S Lines."

The "S Line" is visible only through a special pair of glasses. These lines connect people who have been intimate and disappear when one of them dies. The unexpected visibility of these threads throws society into disarray. It exposes secrets and ignites mystery.

S Line centers on three main characters, Han Ji-wook (Lee Soo-hyuk) is a detective, Lee Gyu-jin (Lee Da-hee) is a mysterious high school teacher, and Shin Hyeun-heup. The latter is a reclusive student played by Arin of Oh My Girl. Shin Hyun-heup has seen these lines since birth.

As Ji-wook begins investigating a series of strange events, Hyeun-heup slowly steps out of her isolation to unravel their purpose. She was previously traumatized by a dark past tied to the red lines.

What quickly became the most talked-about moment of the premiere was the sheer number of red lines floating around Lee Soo-hyuk’s character. An X user, @jinoeuls, wrote,

"lee soohyuk’s character has hundreds of #SLine LMAOOO this is actually so creepy."

The internet erupted with reactions. Fans jokingly calling him a "peacock” and other similar names. The absurdity turned into a viral moment. It drew even more attention to the drama’s premise.

"I'm kinda in shock too. He's turning into a red peacock. Lol," a fan commented. "Why does he have so many lines?," an X user wrote . "Oh man, it looks so good! I like this look! Very different from his usual sleek back hair. But ngl i cackled so hard at seeing so many red lines on top of his head, Imao!! He's definitely a playboy but a fine one," another one said. "REAL PLAYBOY HAN JIWOOK," a fan remarked.

Others humorously dubbed him “a s*x-addict" based on how many connections hovered around his head.

"how many people he sleeping with lol lol," a fan commented. "It's really scary he has a lot of #Sline," an X user wrote. "knets calling soohyuk's character a man with a chicken crown coz look at that many s-lines above his head lmao he a s*x addict detective lol," a netizen added.

---

More about S Line, premiere highlights, and episode release details

S Line is a six-episode fantasy thriller based on a webtoon by Ggomabi. He is also known for A Killer Paradox. It is directed by Ahn Joo-young and presents a disturbing yet creative social experiment, what happens when the most private parts of one’s life become visible to all?

The story builds a chilling narrative of shame, judgment, and self-destruction as more people begin to see these red connections. In the first two episodes, Hyeun-heup becomes involved in an attempted murder case.

Meanwhile, Detective Ji-wook tries to make sense of a growing series of crimes. Seemingly, all crimes are tied to the appearance of these lines.

S Line had its global premiere at the 8th Cannes International Series Festival. It competed in the long-form category and took home the Best Music Award. This marks a significant achievement for a Korean production.

The next episodes of S Line will release in pairs. It is a short but intense watch. Episodes 3 and 4 are set to premiere on July 18, followed by Episodes 5 and 6 on July 25.

---

S Line is available exclusively on Wavve, a paid subscription platform. Notably, the platform does not offer a free trial. Viewers interested in following the mystery as it unfolds will need to sign up on Wavve to access all episodes upon release.

Edited by Tiasha