Female forensic doctor Qin Ruyi discovered on the autopsy table that the handwriting between the deceased's fingernails was the nickname of her twin sister who disappeared ten years ago. As the investigation deepens, she discovers that her sister's disappearance is related to a series of murders, and that her lost childhood memories contain the key to solving the case. What's even more frightening is that the murderer seems to have been by her side all along.
