As a widow, Yeo Hwa cannot leave her home and has to mourn her late husband day and night. However, she often sneaks out at night and helps people in trouble by disguising herself as a man behind a black mask. One day, she hears that Kkot Nim, the little servant she adores, was taken for her father's debts. She goes to the inn where Kkot Nim is and sees Officer Park trying to take her by force.

Yeo Hwa decides to save Kknot Nim by herself. The moment she walks into Pil Inn with her face covered up, she spots Kkot Nim taken away by Soo Ho, the officer of the Capital Defense. Meanwhile, the Minister of Finance summons Soo Ho as a masked man sneaks into his house and steals his precious painting.

Soo Ho realizes Kang Pil Jik of Pil Merchant Guild is also searching for the painting that Yeo Hwa stole from the Minister of Finance. Soo Ho leaves a note to the masked hero at Myungdo Inn to give a warning. Meanwhile, Yeo Hwa attends a relief with her mother-in-law and high officials' wives, and a child goes missing out of the blue.

Soo Ho visits Myungdo Inn to get the painting fixed and runs into the masked hero. She lets him know that Pil Jik has been kidnapping children from shantytown. Soo Ho decides to take care of it as the officer of Capital Defense and tells her to get her hands off the matter. Meanwhile, the King and Yoon Hak look for the members of the late King's guards.

Yeo Hwa and Soo Ho find where Pil Jik has been hiding kidnapped children in Pil Inn. They manage to rescue them but are at odds again about where to take the children. Soo Ho wants to take them to the Capital Defense as witnesses to Pil Jik's crime, but Yeo Hwa wants to send them to a safe place first. Meanwhile, the Minister of Finance passes away, and his servant gets arrested as a suspect of murder.