Yi-jun can no longer hide his feelings for Jae-hee, but Jae-hee must keep her identity hidden until the culprit is found. In order to quell the rumors about them, Jae-hee goes on a blind date with a female Taekang employee. Unable to hold back, Yi-jun confesses, but Jae-hee turns him down despite feeling the same way. On the way to the memorial service, they face their greatest danger yet.

Yi-jun acknowledges his feelings as unrequited love. Jae-hee returns as his secretary and is confused as Yi-jun is suddenly being nice to her. Si-a's presence makes them keep their distance from each other. Hye-jung gets involved in the investigation on Han Eun-young's death, and she reveals she is being threatened and followed. The culprit is on the move, and Yi-jun and Jae-hee fall into danger.

Yi-jun kisses Jae-hee but insists that he sees Jae-hee as a little brother and continues to nitpick. Meanwhile, the investigating team summons Hye-jung as a witness, shocking Yi-jun and Si-hyun. To make matters worse, Chairman Yoon is putting pressure on Yi-jun as well. Overwhelmed by the pressure and confusion, Yi-jun pushes away Jae-hee, who eventually has enough and says she will quit.

Jae-hee can't remember what happened the previous night and is anxious if Yi-jun is crabby because he got wind of her true identity while drunk. What's worse, Yi-jun's fiancée, Lee Si-a, returns from France. Yi-jun feels confused but stays cold toward Jae-hee, and Jae-hee is upset when Yi-jun goes to have dinner with Si-a. After much searching, Jae-hee finally gets hold of the key evidence.

The investigating team finds traces of herbicide in the milk and suspects that someone is after Yi-jun. Jae-hee keeps an eye on Yoon Na-jung, the ambitious second daughter of Taekang, and follows Yi-jun to the family dinner, which is full of tension. Chairman Yoon makes an unexpected decision, causing a stir. Jae-hee joins Yi-jun for a drink and her drinking habit starts coming out.

Yi-jun stays prickly but starts trusting Jae-hee. Jae-hee notices something suspicious about the milk Yi-jun was drinking and realizes he is being threatened. The investigating team thinks the perpetrator could be someone else. Jae-hee finally gets the chance to enter the room that's been banned from entering. She searches for the missing phone in the room but immediately faces danger.

Kang Jae-hee's double life begins. She's Yoon Yi-jun's secretary by day and a detective by night. Yi-jun keeps testing her, but Jae-hee relentlessly keeps an eye on him and searches for the missing phone. She plans to infiltrate the room that's banned from entering, but Yi-jun doesn't let his guard down easily. Their relationship takes a strange turn through unexpected physical contact.

Taekang Group's successor, Yoon Yi-jun, is suspected of murdering his secretary, but the group's power and lack of evidence impede the investigation. To find key evidence, special forces-turned-detective Kang Jae-hee applies to be his secretary, not as a woman but as a man! She manages to get the job, but Yi-jun doesn't let his guard down. Jae-hee risks getting exposed on her first day at work.