Genres: Thriller, Mystery, Fantasy

The show will tell the story of a mysterious red line that appears above people’s heads, connecting them to those they’ve had sexual relations with. Han Ji Uk is a detective who wants to discover the truth about the mysterious red line. Lee Gyu Jin is a quirky high school teacher, and Sin Hyeon Hop is a high school student who has been able to see the red line since birth.

Adapted from the webtoon "S Line" (S라인) by Little Bee (꼬마비).