Season 1

2025 | 6 Episodes

Season 1 of S Line premiered on July 11, 2025

Han Ji Wook is a detective looking to know what is the truth behind the mysterious red line. Kyu Jin, a funny high School teacher. Hyun Hob, a high schooler who has been able observe the red line from birth. The show will present the story of a cryptic red line that appears over head of the people in the show, connecting them to people with whom who have had sexual relations with them.