As a single mother, Li Qingcao experiences problems finding a good school for her daughter. Once a 'leftover child' herself, she wants to offer a brighter future for her daughter. Meanwhile, the remains of a man murdered years ago are found in Li's hometown. The decade-old murder case has now become incredibly complex and confusing, surrounded by mysteries. On a rainy night, Detective Han Yan returns to the crime scene for investigation and suddenly discovers a connection between the case and several left-behind children, unraveling both Li Qingcao’s secrets and his own in the process.