A year ago, 13 people from different classes bullied the introverted and cowardly girl (Robin) in the school, which eventually led to the girl's suicide. However, 13 people concealed the truth and claimed that they didn't know, so they covered up the story. Until one day, 13 people were kidnapped at the same time. When they woke up again, they found that there was only a broken wooden house in a cold mountain without signal Campfires and wooden posts engraved with nursery rhymes. Here, in the face of dark nursery rhymes, they seem to see the wronged souls of Robin and revenge them...