Season 1

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.

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.

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.