Following her father's murder, a revenge-driven woman puts her trust in a powerful crime boss — and enters the police force under his direction.

With the help of a gutsy female detective, a prosecutor who has lost the ability to feel empathy tackles a murder case amid political corruption.

Do Won and Seo Kyung both lose their fathers on the same night 12 years ago. In the present day, Do Won is a police officer and Seo Kyung a prosecutor. The police discover several skeletons on the train tracks at Mukyeong Station, which has been closed for five years. Do Won heads to the station while chasing a key suspect.