It's been two years since 32-year-old Hyo-jin lost her husband in an accident. One day she receives a request to take in 16-year-old Jong-wook, the son born to her late husband and his ex-wife, after his grandmother develops dementia. She does not feel comfortable with this, but ultimately agrees.
Hyo-jin tries to get friendly with Jong-wook, but he does not. Later she discovers that Jong-wook is going around looking for his biological mother. She was told that his mother had passed away, but now she begins to question whether she might still be alive.