Taehwa receives a lung transplant from his father, who had committed a hit-and-run the night before the surgery. Riddled with guilt, Taehwa sets out to find the victim’s daughter Miji.

此剧改编自同名网漫，讲述有一天人类的头顶出现了肉眼可见的红线，这条线连接到了与自己有肉体关系的人。在一夜之间展现了自己阴暗面，现实地讲述了各种社会故事。