when hee-joo (shim eun-kyung) was 7-years-old her father was murdered. her father worked as a detective and was working on a serial killer case. the killer, ki-bum (kim sung-oh), was eventually arrested, but found guilty for only one murder. 15 years later, ki-bum is released from prison. detective dae-young (yoon je-moon) worked on the original case with hee-joo's father and he has not given up getting a murder conviction for his former partner. meanwhile, hee-joo has waited patiently for kim-bum's release.