Jeon Jungkook is a Guardian of Red String. His job is to tie a red string of fate to two people’s pinky fingers. The two people are soulmates. He decides which person is the most compatible to other person. He makes no mistake. Sometimes he feels lonely because no one, but the Guardians, can see him. No human beings can see Guardians of Red String. That’s until he meets Kim Haerin.

Kim Haerin was just a normal woman who works as a doctor until the accident that almost costs her life. After that accident, strange things happen to her. She sees a lot of red strings tied to people’s pinky fingers. She sees Jungkook and other Guardians.

Jungkook wants to find out about his past life. She decides to help him. Along the way, they fall in love. A forbidden love. No humans are meant to be with The Guardians of Red Strings. What will happen then? Will they give up? Will Jungkook find a suitable man for Haerin? Or will he stay with her until she dies?