In 1800, Joseon. Sixteen-year-old orphan Sol takes a position at the police station and becomes the assistant of a young inspector, Han. Together, they set out to investigate a high-profile murder of a young aristocrat.
The deeper Sol and Han delve into the secrets of the deceased, the stronger the trust between them grows. But suddenly, it is the inspector who turns out to be the main suspect in this baffling case…
Sol is trapped: it seems that only she can uncover the truth and name the real killer. Will the girl be able to solve the crime when she can hardly rely on anyone?