In the third episode of "Filing for Love," Ki-jun is caught off guard by an anonymous email alleging that I-na is having an illicit affair. As one of the workers tries to plead with I-na not to get him fired for his misdeeds, Ki-jun observes the situation with bated breath. Thankfully, the man walks away, and they return to their usual business.
Meanwhile, Ki-jun decides to postpone his resignation to investigate the claim against I-na. He apologizes to her, and she assigns him more menial tasks like shredding papers. When one of the workers chides him for getting on I-na's wrong side, Ki-jun becomes more determined to bring her down.
The next day, Ki-jun ponders the importance of distinguishing between foes and friends in the workplace. In contrast, Gwang-II arrives at work in his usual cheerful mood, greeting everyone and helping the kitchen lady carry a few things. On the other hand, Ki-jun arrives ready to take down I-na.
Speaking of I-na, she asks Jae-yeol to consider making the audit team more independent. He refuses, but she asks him to reconsider and leaves the meeting early. Jae-yeol is displeased when he learns from Se-young that his dad ordered the return of Sung-yeol. When Se-young gets a call from his dad, he picks it up and tries to reason with the Chairman, but the old man wants Sung-yeol to boost the shares for their construction company.
Later that night, Ki-jun secretly follows I-na as she heads home. He notices that she stops at a convenience store and checks the trash to get her receipt. He finds nothing suspicious and only learns that I-na is a light eater. He talks to the convenience store attendant, who claims that she has never seen I-na with anyone and only praises her beauty, tricking Ki-jun into buying stuff for her and her boyfriend.
A-jeong teases him when she sees how much he spent at the convenience store. When he tells her about the food I-na buys, she reckons that maybe I-na is unhappy and only does the minimum for survival. However, she never realizes that Ki-jun is talking about I-na.
Back at the office, Gwang-II has dinner at the company's cafeteria and overhears two employees talking about the return of Sung-yeol. They gossip about who the chairman will support and who they should align themselves with. They believe that Jae-yeol will be overlooked because of his mother's mental illness.
Gwang-II observes that Jae-yeol's influence extends beyond his own capabilities, thanks to his arranged marriage, and cautions them to be wary. On his way home, the elderly kitchen lady he had helped earlier calls him aside and offers him the leftovers from the executive meeting as a token of gratitude. She also presents him with a sum of money in appreciation for his assistance during her husband's passing. Despite his twins' needs, he declines the offer, but she insists, grabbing his hands. An onlooker captures this moment in a compromising photo.
Gwang-II returns home to the warm embrace of his wife, who appreciates the delicious food. Meanwhile, Sung-yeol's return sparks unwanted attention on the work chat page, leading to gossip and speculation. Se-young requests the HR team to intervene.
The HR team leverages the compromising photo of Gwang-II and exaggerates the situation, shifting the focus from the sibling dispute to an alleged affair with the kitchen lady.
At Team Three's office, Ki-jun delves into I-na's personnel file without her knowledge, finding nothing suspicious. I-na, unaware of his investigation, continues to tease him with playful antics. Surprised by her sense of humor, Ki-jun finds himself smiling at her.
As the Gwang-II alleged affair escalates, I-na orders an investigation and suspends Gwang-II from work. He attempts to clarify that the rumor is unfounded but is still subjected to an interview. Upon returning home, his wife is unconvinced by his explanation and sends him away.
Meanwhile, Ki-jun follows I-na and discovers her attending an art class, questioning whether he's overthinking the situation.
The next day, employees are shocked to find Gwang-II sleeping in the office. I-na revokes his access and asks him to leave until the investigation is complete. On his way out, he encounters the kitchen lady's son, who angrily blames him for his mother's job loss. The confrontation causes a disturbance at the company, shocking Gwang-II and leaving the team heartbroken at his distress.
Min-su arrives to deliver the investigation results to Gwang-II. Although he didn't have an affair, he will still be reprimanded for what happened with the kitchen lady's son. The team decides to take a stand against this unjust decision, and Ki-jun reluctantly agrees to join them.
They head back to the office and summon I-na to the rooftop. There, they enumerate their grievances and demand that she withdraw the disciplinary action against Gwang-II. She explains that Gwang-II took food from the company and gave money to an outsourced staff member. She questions whether it's the right thing to do to withdraw the disciplinary action, as it might make other teams accuse the audit team of getting special treatment. After the meeting, Team Three decides to take a day's leave in protest. However, I-na doesn't even react to their absence.
The team begins to worry that they made a mistake and sends Ki-jun to check the vibes. He overhears I-na's conversation with Se-young. It turns out that I-na figured out that the HR team is using Gwang-II as a scapegoat to protect Sung-yeol and Jae-yeol.
She asks Se-young to take down the post since it has been confirmed that Gwang-II is innocent. Se-young refuses, saying that they need to cover a rumor with another rumor. Without missing a beat, I-na grabs Se-young's hair and starts to fight. As expected, their fight becomes the hottest topic on the work chat.
Later that night, Ki-jun saves I-na when the fired employee comes back to threaten her in the parking lot. She ends up hurting her finger, and he gives her first aid. He finally confesses that he had misunderstood her and asks why she lets people misunderstand her actions.
She calmly explains that it comes with the job. She will always have to choose a side and make enemies either way. She believes that a leader can't be non-committal. She is moved that Ki-jun sees the intentions behind her choices. However, she steals the noodle cup she bought for him as a token of gratitude for helping when he calls her a psychopath.
Meanwhile, A-jeong returns the keys to the studio apartment to Jae-yeol and refuses to tell him where she is currently staying. She claims that she wants him to worry about her. On her way home, I-na sees Jae-yol's car parked outside her apartment and takes a U-turn.
The following morning, Sung-yeol makes his official return to the office, and Jae-yeol tries to act nonchalant. Meanwhile, I-na tries to warn Gwang-II about how people might misunderstand his kind actions. He clarifies that he can't change because being kind gives meaning to his life. He sees the kitchen lady off, and they thank each other. Thankfully, she got a better job offer elsewhere.
Team three realizes that I-na is not as bad as they thought and starts acting kind and considerate towards her. Da-ye also decides to be kind to her team and give them access to her candy box. That night, Ki-jun follows I-na to the art studio and realizes that she isn't carrying any art supplies with her. He goes inside to investigate and realizes that I-na is a nude model. The episode ends with a naked I-na, shocked to see Ki-jun.
