On a full moon night, a ten-year-old girl from a farming family in a remote village is lured by Moosina into a cave in the mountains, where she uncovers the secret about why the mountain demon always plays dirty tricks on children.

A love story that starts with pretending to be sick, describing a troubled teenager named Ye Zijie who always loves to get into trouble. By chance, he discovered that "it's good to be sick".