Han So-Yoon, a Korean woman living in exile in Canada, returns to her homeland after taking a job as an English teacher in a small village called Achiara. On her first day of work, she unwittingly unearths the body of a young woman, apparently the victim of a serial killer.

Seo Yoo-Na gives her statement to Officer Park Woo-Jae after she was assaulted in the street. So-Yoon asks more questions about Kim Hye-Jin, the missing woman.

So-Yoon makes a curious discovery about her sister while Agent Woo-Jae investigates Kim Hye-Jin's disappearance. Meanwhile, Yoo-Na and Ga-Young put themselves in danger.

The investigation into Kim Hye-Jin's disappearance turns into a murder case after new evidence is uncovered. Seo Gi-Hyun offers his help to So-Yoon in order to find Kim's sister.

So-Yoon hires a detective to find her sister, but to no avail. The young woman is troubled by the resemblance between her sister and Kim Hye-Jin. Yoon Ji-Sook panics at the thought of a scandal tarnishing her family.

A funeral is organized for Kim Hye-Jin by her mother, while the identity of the deceased is increasingly called into question. Ji-Sook urges her husband to have another child.

Now certain that Hye-Jin was her sister, So-Yoon sets out to find the deceased's biological family, whom she suspects of being involved in Achiara's dark secrets.

The villagers have become hostile towards So-Yoon since the revelation of her connection to Kim Hye-Jin. The young woman, aided by Agent Woo-Jae, is searching for information regarding her sister's adoption.