Jo In-a, a young girl, finds her uncle murdered next to a puzzle piece, but she cannot explain his presence at the crime scene. The incident haunts her for years. Ten years later, In-a works as a crime analyst and is confronted with a murder case where the victims were found next to puzzle pieces, similar to her uncle's murder. She teams up with Han Sam, a sharp but mysterious detective, to follow the clues. Their investigation leads to Hyun Bong-sik, a cunning criminal, and Choi Sun, a suspect with a dark past. Along the way, In-a encounters family secrets and the connection between the murders and her own life. Mysterious characters such as Kim Ye-won and others, whose identities are gradually revealed, add to the complexity of the...