Detective Oh Jin-Sung moves to Seoul as part of prosecutor Cha Young-Woon's team to help with the case. After arresting Bae Min-Gyu, and having to let go of him due to his alibi, Jin-Sung strengthens his resolve to prove he's the killer. However, what he couldn't foresee was that his younger brother Oh Jin-Woo will be arrested due to abundance of evidence pointing to him as the likely suspect.