Han Yoon-Seo works as an investigator for the Human Rights Promotion Commission. She investigates cases based only on the only facts, while trying to stay impartial throughout the investigation. Because of this, she is often mistakenly thought to lack empathy. Han Yoon-Seo also carries a secret and an emotional scar from her past that she cannot tell anyone. Bae Hong-Tae is a former prosecutor. He was dispatched to the Human Rights Promotion Commission and began to work as an investigator for that organization. He is righteous and tends to act before thinking things through. Han Yoon-Seo and Bae Hong-Tae have conflicts on everything, but they work together for the people who need their help.
