A kidnapper disappeared 15 years ago without a trace. Five days before the case's statute of limitations expires, someone is found anonymously leaving a flower at the crime scene. A few days later, another kidnapping takes place using the same method on a similar target. Police team up to solve the case before it's too late as in its previous case. Detective (Kim Sang-kyung) is consulted and he confirms its a similar MO.
Later it turns out to be the child's grandfather (Song Young-chang), was the perpetrator of the first kidnapping 15 years ago. This was found out by the mother (Uhm Jung-hwa), and she kidnaps his granddaughter using the same MO. She thought the guilt will make him confess his past crimes. The detectives find out, confront the grandfather, and make a deal with him. He confesses his sins and goes to prison. Everyone involved in the long-unsolved case finds closure.