Years after surviving horrific abuse in high school, a woman puts an elaborate revenge scheme in motion to make the perpetrators pay for their crimes.

In a cutthroat world where the life you’re born into decides your success, three aspiring youths are determined to change that perception as they fight for their dreams.

The Subway Police of Wangsoori Station is led by Chief Inspector Ko Ji Seok. He is the best of the best, although his only goal in life is to have a stable, uneventful career. However, a serial killer, nicknamed "the Subway Ghost", strikes the Subway Police 30 Year Anniversary event. An applicant shows up for a job interview to join the team.