Im Dong Hwan's father, Im YoYeong Gyu, is a master craftsman of seals even though he is visually impaired. One day, Im Dong Hwan receives a phone call from the police. He is informed that his mother Jeong Yeong Hui's remains were discovered. She went missing 40 years ago.
Im Dong Hwan, who never knew his mother's face, hears that there is a possibility that his mother may have been murdered. Im Dong Hwan begins to trace Jeong Yeong Hui's death with PD Kim Su Jin, who was filming a documentary about his father Im Yeong Gyu. They interview people who worked with Jeong Yeong Hui at a Cheonggyecheon clothing factory about 40 years ago.
