A crime-thriller drama about the relentless pursuit of a Prosecutor toward the man who murdered his first love, while the statute of limitations is getting closer. Prosecutor Cha Woo Jin (Chun Jung Myung) lost his first love, Kim Seung Hee (Kim So Hyun) 15 years ago. He then meets a high school girl, Jo Eun Bi (Kim So Hyun), who looks like his first love. Their meeting unleashed secrets and chain of events between Cha Woo Jin, Seung Hee, Jo Eun Bi, and the criminal.