In the first episode of tvN's weekend drama "Secret Audit," Joo In-ah, played by Shin Hye-sun, made her first appearance as the head of the audit office at Haemu Group.

As soon as Joo In-ah was appointed to the Haemu Group audit office, she transferred Noh Ki-joon (played by Gong Myung) to Audit Team 3. Audit Team 3 mainly handles cases of public misconduct and workplace affairs, and Noh Ki-joon was suddenly demoted from Audit Team 1, where he had been the ace. Noh Ki-joon resisted, saying there was a case only he could handle, but Joo In-ah showed a firm attitude by ordering a handover.

Meanwhile, Park Ha-sun made a special appearance as the wife of Deputy Son, who reported her husband's workplace affair. Deputy Son's wife suspected an affair as her husband spent more time working with Deputy Jung, and she came to Noh Ki-joon with a long hair strand found on her husband's clothes as evidence. However, Noh Ki-joon saw that the two were just working and discarded the hair, telling the informant to visit a hospital and implying she was suffering from delusional jealousy.

Later, after reviewing the report submitted by Noh Ki-joon, Joo In-ah became suspicious of the relationship between Deputy Son and Deputy Jung and instructed the team members to return to the office and wait. As a result, the team members witnessed Deputy Son and Deputy Jung kissing in the office, revealing the affair to be true.

During this process, Deputy Son's wife, unable to contain her anger, drove a car toward Noh Ki-joon and Joo In-ah. Noh Ki-joon protected Joo In-ah and dodged the vehicle, but when Deputy Son's wife approached wielding a metal pipe, he stumbled backward and fell. Joo In-ah supported and protected him.

Park Ha-sun powerfully portrayed the wife's rampage driven by suspicion of her husband's affair. Joo In-ah and Noh Ki-joon showed a dynamic of bickering yet protecting each other.